I'm also getting the error posted a few pages ago dealing with athletic tone.
<?xml version="1.0" encoding="utf-8"?>
<ScriptError Version="6" Type="MiniScriptError" MaxRecursionDepth="0">
<ExceptionData>simulating object is null
unable to obtain an interaction object
A null value was found where an object instance was required.
#0: 0x00014 ldfld.r4 in Sims3.Gameplay.Skills.Athletic+QuickBurstTone:OnSelectionBegin (Sims3.Gameplay.Interactions.InteractionInstance) (1555B500 [15D2AC30] )
#1: 0x0006f callvirt in Sims3.Gameplay.Interactions.Sims3.Gameplay.Interactions.InteractionInstance:SetCurrentTone (Sims3.Gameplay.Interactions.Tone) (15D2AC30 [1555B500] )
#2: 0x00024 call in Sims3.Gameplay.Interactions.Sims3.Gameplay.Interactions.InteractionInstance:set_CurrentTone (Sims3.Gameplay.Interactions.Tone) (15D2AC30 [1555B500] )
#3: 0x0014a callvirt in Awesome.Awesome.Athletics:AutoSetTone (Sims3.Gameplay.Interactions.Interaction`2) ([366128176/0x15d2ac30] )
#4: 0x0001b call in Sims3.Gameplay.Abstracts.AthleticGameObject+WorkOut:ConfigureInteraction () ()
#5: 0x0000b callvirt in Sims3.Gameplay.Interactions.Sims3.Gameplay.Interactions.InteractionDefinition`3:Sims3.Gameplay.Interactions.InteractionDefinition.CreateInstanceFromParameters (Sims3.Gameplay.Interactions.InteractionInstanceParameters&) (05011310 [vt:0F4789C4] )
#6: 0x00010 callvirt in Sims3.Gameplay.Autonomy.Sims3.Gameplay.Autonomy.InteractionCandidate:CreateInstance (Sims3.Gameplay.Interactions.InteractionInstanceParameters&) (187B3960 [vt:0F4789C4] )
#7: 0x00032 callvirt in Sims3.Gameplay.Autonomy.Sims3.Gameplay.Autonomy.Autonomy:AssignProbabilitiesAndChooseInteraction () ()
#8: 0x000c3 call in Sims3.Gameplay.Autonomy.Sims3.Gameplay.Autonomy.Autonomy:RunAutonomy (Sims3.Gameplay.Autonomy.CommodityKind,bool) (18B1B460
#9: 0x0001b ret in Sims3.Gameplay.Autonomy.Sims3.Gameplay.Autonomy.Autonomy:RunAutonomy (bool) (18B1B460 [1] )
#10: 0x00004 pop in Sims3.Gameplay.Autonomy.Sims3.Gameplay.Autonomy.Autonomy:TryFindBestAction () ()
#11: 0x0002a leave.s in Sims3.Gameplay.Autonomy.Sims3.Gameplay.Autonomy.AutonomyManager:Simulate () ()
#12: 0x00022 ldc.i4.0 in ScriptCore.ScriptCore.ScriptProxy:Simulate () ()
Once it starts, it keeps happening every couple of seconds when I have the enablescripterror package loaded. It sometimes also crashes from it. I'm not sure, but it may only be crashing when I don't have enablescripterror loaded. (If you're wondering why sometimes I don't have it loaded, it's because I have to either take it out or re-add that package every time I launch Sims to get past the loading crash. One of the two gets it to start back up normally.)
In case it's somehow related, my sims are level 10 athletic, so they have the full set of different exercize types. I also have the full HystericalParoxysm more realistic skin textures installed.
Hope that helps!