Going to throw this out there...but my phone acted ******ed with force closes if I didn't reboot it regularly. If I rebooted once a day I didn't have force closes, but if I didn't do a reboot I'd get random force closes.
I have since rooted and went with a newer ROM and haven't gotten a good feel for the new stability, but so far it seems to be roughly the same (had Pandora force close on me today twice).
From what I read it's apps that you use frequently, and Davilik's garbage collection. It seems that Android 2.3 has better garbage collection to resolve these issues.....