Have you downloaded any camera mods?  I find that some of them act strangely on my new computer.  Gunmod's cameras worked perfectly when I had XP, but were a little odd with Vista.  I downloaded some by Tom420, and they work much better for me.  I do still use Gunmod's live camera, which seems a little more precise than Tom420's.  (link - 
http://www.modthesims.info/download.php?t=312294)
If you haven't downloaded any camera mods, you might benefit from trying them out.  Just back up the original files, so you can go back to them if you need to.