When I press "p" to test the game some of my meshes and stuff rotate and change position. I don't understand why. I don't have any ipo's or anything like that attached to them. Please help me if you can!

Perhaps this is because in some situations you need to press "Ctrl+A" to your meshes before playing the game.

Probably you have to disassemble your hierarcies, do ALT-P and rebuild the parentings.

Also NKEY can help to find the "weird" object (look for scalings -1 or such)

carsten