You may want to try the old uninstall/reinstall (if you haven't already). I haven't had any problems, and I'm running a PC with a 533 mhz Celeron and 128 megs of ram, so it's not exactly state of art or anything. Unless your computer's even older and feebler than that, something's not set quite right. It certainly doesn't seem to be any bug inherent to Carrara. As Litst alludes to, maybe something is running in the background, sucking up your resources without you knowing? Or maybe you've got a virus in there... shudder