I can't find the source of my problem, but my 1.1.1 jailbroken iphone continues to crash a lot, at seemingly random intervals when I'm using 3rd party apps. The entire phone will freeze and the only way to fix it is holding down power and home to reboot it. I DO NOT have summerboard installed. I have no clue what could be causing this problem. I've even had it crash before when i had mobilechat open then put my iphone into standby then tried to take it out of standby and it wouldnt work, and I had to reboot it. It's also crashed while I've had say an IRC client, and mobilechat open while I'm browsing in safari.

bump. I just restored my iphone rejailbroke it and reinstalled all my apps but im still having this problem.

its obviously one of the apps you put on it, restore your phone but dont put the apps on and the problem should stop. (if it doesnt you know there is a bigger fish to fry) then slowly add your apps till you find the problem one (and by slowly i mean one a day so you use the phone enough to see if its going to crash)

also check this out