I've been having a problem with the CK - I place things (mannequins, weapons, statics, etc), and carefully line them up, rotate, etc. so they look nice. Problem is, when I load up the game, stuff isn't where I placed it. Things end up under ground, above, generally not where I want them.

Any ideas? Fixes?

It's probably a game problem

Are they havok settling? There's the Run Havok Sim button in the CK.

Are you loading a clean, never used save-game?

I've had issues too that I thought was the CK being bugged, but I've been able to resolve them, including NPC placement, but I still occasionally see weird things so not ruling that out.