Mine was doing this after root on. 602. I just SBF. 602 and reapplied root and all is well. Matter of fact, the phone is working better than ever. I suspect that the upgrade route from froyo to gingerbread to newest gingerbread probably left behind some problems. I was never a believer in OS upgrades and much prefer clean installs.
using the sbf for .602 definitely did the trick...however, i started to notice that as I freeze bloatware it started to do it again (i'm not freezing anything major either: ie skype, google talk, amazon, etc.