try a battery pull, leave the battery out for about 5 minutes and then see if that helps. mine was doing the same thing and i was doing battery pulls a lot, i deleted all of my prior text messages and now it works like it's brand new...
that's my advise =)
Latest os, I think 5.0. I might have had too many apps open. I closed some of them, and now it seems better. Thanks for the quick responses.
Glad it's working better for you. Just remember to keep up on closing apps you're no longer using and that should help. I know occasionally mine locks up with 5.0.140, but that happens when I haven't used it for a little bit and then I all of a sudden start using it like crazy lol
Personally, I think that OS .151 has been the best OS we've had in regards to managing memory and memory leaks. If you're having memory issues, I recommend you move to this. You said that you think you're on OS 5.0. I don't understand how you can think as opposed to knowing what OS you're running. You are the one that would have installed it and it's not something that you forget.
Next time you have the clock (repeatedly), go to options>memory and tell us how much your application memory free space is.