I would... Restore then rejailbreak. If it still does it then jailbreak with a custom firmware using pwnage tool. Otherwise... Did you back up your shsh blobs before you went to 2.1? If so you can always go back to 2.1 then rejailbreak using limera1n or greenpois0n, however those will be a tethered jailbreak. Good luck
I think I found the problem. I went through the jailbreak one by one. BiteSMS may have been the problem. I jailbroke my phone for the 6th time. I left BiteSMS off. And for the first time, my phone is not crashing. My fingers are crossed.