My computer used to run fine on Leopard, then i installed snow leopard and it constantly has moments where it crashes all the time. It basically shows that wheel on any application (a usual suspect would be Firefox, which i've never had trouble with before) for maybe 30 seconds and then goes back to normal for another few minutes or it freezes on an application and it needs force quitting to get it working again. I can go whole sessions without this happening then other times i'll turn it on and it won't stop crashing like that. I'm on the 10.6.2 update version. Any ideas?