The Headmaster is one of the buggiest scenarios in the game.  Here are my tips for "headmaster hygene":

1. Save the game BEFORE inviting the headmaster.
2. Don't invite him over far in advance.  Wait until 4pm or so on the day you want him to arrive.  Espescially don't invite him the night before.  That will virtually guarantee the vanishing headmaster bug.
3. Do not save after you invite him.  That will virtually guarantee the snooty-immediate-rejection bug.
4. Do not save again at all until the scenario is over and he's left the lot.  If something goes wrong, it can bug your lot (use FFS lot fixer).
5. Have somebody right at the curb at 5pm to greet him.  This may mitigate the snooty-immediate-rejection bug, and is part of the next tip.
6. Don't let him out of your sight.  There are objects that he'll get stuck on and you'll be screwed.
7. Keep him away from hot tubs.  You don't want the "headmaster in the hot tub" bonus.
8. If he gets stuck, or disappears or does anything strange, quit without saving to avoid bugging your lot!
9. Turning off free will might be a good idea so you don't have to keep track of your sims and the stupid headmaster and his swarm of bugs at the same time.
10. Complete the scenario as quickly as possible to reduce the likelyhood of something bad happening.  Other posters tips are all good.
11. Don't have social interactions with the headmaster outside the scenario (don't call him on the phone to chat), it can trigger more bugs.  For God's sake, don't move him in or marry him.

Or, once you've done it once or twice and realized that it's pretty easy, and you don't want to risk bugs, just cheat.

The Grim Reaper doesn't have any facial structure data, so any offspring produced with him will have the default face (i.e. the first in the list.)  For females, it happens to be quite similar, but not identical to Hula Zombie (Hula's face is a bit shorter and rounder.) He does seem to acquire a SimDNA entry somehow, but it seems to vary from game to game and neighborhood to neighborhood. The offspring's genetics (skin, hair and eye color) will be as expected for normal breeding, but the face will be the default.  The Therapist and Hula have complete facial structure and DNA information (fugly and attractive respectively) so breeding with them goes more normally.  The remote control car has a similar result to the Reaper.  Other "special" NPCs like the social bunnies are regular mutant townie sims under their costumes and have no special results when breeding.

It may be most fun to dispatch them without cheats.  If you'd like to do that, the quickest and easiest routes (in order of speed of death) are probably:
1) Fire: stick them in a doorless room with a fridge and an oven and stacks of furniture.  Stick something in the oven, but cancel before they retrive it.  Let flamage ensue.
2) Drowning: pool + swim - ladder = glug glug glug
3) Starving: my favorite route is to lure them on to a solitary piece of decking or foundation then delete the stairs and switch to max speed.  Don't give them room to even lay down.  They'll be on display like David Blane until they finally bite it.
4) Flies: Unless the unlimited trash piles via pizza bug has been fixed since I've last done this, flies is a pretty easy and fun death.  Use the pizza box bug to create a long corridor filled with trash, and march your sims through the mess.
5) Fright: If there are already a enough ghosts to get regular hauntings, this can make short work of a sim.

Other methods require cheats or are slow or require a complex setup or would require cheating on a dorm lot.

See PeeWee's Death Tutorial.

If you just want to do them in quickly, Rodney's Death Creator is the way to go, or buyable fire.  Play your cards right and you can take out a few pesky dormies while you're at it.

Thanks for the replies.  Looks like I can just ignore it...

If by "tested my RAM" you mean anything other than pulling out your DIMMs and trying it with modules known to be good, then you haven't tested your RAM.

Here's what I'd check for in the order I'd check them:
1) Stop overclocking if you're doing that
2) Update your video drivers
3) Update your sound drivers
4) Borrow some RAM to try
5) Borrow a video card to see if yours is flaking out
6) Same with sound card (if you're not using on-board sound)
7) Try underclocking your CPU
8 ) Find some way to test for the remaining really annoying possibilities - flaky motherboard or processor.

I'm having the problem described in this thread and this thread.  I have a sim who has all the necessary skills for her major/semester, but her grade meter is stuck at the lowest position.

A couple possibly relavent details:
1) She's an ex-NPC (cheerleader)
2) University is the only expansion I have.  I do have the post-Uni patch.
3) It's a fraternity lot I founded, not a maxis lot.

Things I've tried:
1) Lowering then regaining her skills to try to get it to re-fix it.
2) Changing majors with the college adjuster.
3) Fiddling with the semester/grade/etc. with the college adjuster.
4) Moving her out of the lot then back in - this has worked for me in the past every time, but for her, her meter is fine once she's on another lot, but gets screwed up again once she's back.
5) Moving her out, completing a semester, moving her back in (same effect as above)

I am not going to bulldoze the lot - I'd kill this particular sim first, but I'd like to find a solution in case this happens to a more important sim in the future.  This is a lot I'd like to keep using, so if it's bugged, I'd like to fix it somehow.  I've heard moving everyone out, lotbinning, packaging, then re-deploying a lot can squash bugs in it.  Does it work, or is that just an urban legend?  If so, is it possible for the lot to keep all its objects (custom paintings, tombstones, etc.) intact?

I don't know if you've gotten confirmation yet or not that your untested version works with Uni, but I just tested it with my game (only the base game plus Uni), and it seems to work perfectly.

Actually, that might have been the second time J. M. Pescado had asked that (perhaps once at varioussimmers also).  I recall asking him in why he had a burninator for an avatar when he was a fat obstreperous jerk.  On the Nethack IRC channel, I get someone asking me about my handle every 5 seconds.

That's weird...  I looked at her again in SimPE, and the "Is Ghost" box is checked, which I hadn't looked for before.  I suppose that's why zombie/ressurection wants and fears are showing up, and why she's gray in the family tree...

1) His name is Goopy.
2) His name is Goopy.
3) I wanted an inverted "nice" zombie, and he happened to be handy.

That seemed to have the desired effect - her character data did not get toasted.  Everything seems to be mostly OK now except two things; she still shows up as gray in the family tree, and she still is afraid of being a zombie.  But nobody wants to ressurrect her anymore, and I was able to delete the tombstone safely.

I probably should upgrade, you're right, but I have such a hard time justifying it when I only play it once-in-a-while, and hate giving Maxis more money to fix their stupid bugs.

Edit: Oh, and thanks for backporting the hack, I didn't mean to be such a pest/fathead.

Is there any way to accomplish the same thing manually?  I presume backing up the character file, then restoring it after the tombstone has been deleted is not sufficient...  Could I ressurect her with the reaper-phone (on the lot with the tombstone), then reset her age to what it should be and move her back to her correct lot?

I see that hack in the NL directory, but not the UNI directory.  I do not have nightlife - is that hack uni-only compatable?

I've got a little bit of a problem that I don't know how to solve without damaging my neighborhood...

In one of my houses in pleasantview, I fed Goopy to the cow plant.  Then I turned him into a zombie, then I drowned him, then I ressurrected him with about 5k to invert his personality and make a "nice" zombie.  Everything seemed fine.  Then I moved him out.  This was a little while ago.  The next time I played the house, I noticed there were several tombstones and urns near the cowplant.  I had assumed I had left the cowplant door unlocked, but no, it's locked.  There's no way to get to it.  Then I noticed that all but one of the urns/tombstones weren't assigned to anyone.  The tooltip just "urn/tombstone" not "Joe" or anything.  The one is assigned to a person who is very much alive.

If I go to the lot where that person lives, she's at work, but everyone in the family wants to ressurect her.  But she comes home from work just fine - but she's afraid of becoming a zombie.  She shows up as gray in everyone's family tree, but nobody has a memory of her dying.  In SimPE she does have an "I am dead" token, but she's walking around just fine in spite of it all.

I'd like to repair things, but I'm not sure how to do it without causing even bigger trouble.  I only have 357 or so character files, so I don't think I'm even approaching fireball status yet.  I'd like to keep this sim alive - at least for the next six days or so when she's going to kick off from old age.  I'd like to also delete those bogus tombstones without deleting her charcter data.

I wouldn't let support or non-support by the distro for a particular resolution factor into your judgement of which distro to use.  You can just add a modeline to your X config if your distro doesn't do it for you.  It's kinda confusing if you haven't done it before, but you only have to do it once.

Actually, expensive art can appreciate or depreciate with apparently equal odds.  Usually it's only by a few percent anyway, so it makes a tiny difference at worst.  Even then, it's more than made up for by the improvement on the viability of chance cards.

OK, something that hasn't been mentioned here, but should factor in to any chance card junkie's stategy...  You shouldn't leave money lying around unspent for chance cards to take away.  If you have more than a couple grand in cash, buy a bunch of art and stash it in your basement (preferrably someplace unreachable by burglars).  If you don't have money, chance cards can't take it away.  When you need to drop 20 grand on that expansion you've been saving up for, sell off some of the art.

With big monetary penalties nullified, a lot more chance cards become worthwhile.

I presume it is legal to use the potty-training potty for toddlers, as there is no other way for them to do their business, and no other way to accomplish potty training...  Just wanted to verify before I started producing the little buggers...