Default CWM is making me nuts

I am getting very upset because every rom I try to recover using CWM produces a problem. Im trying to restore different android version ROMs and I dont understand how can them be SO INCOMPATIBLE with each other, since the core should be compatible. I am always restoring to stock and even then the rom restore fail, usually indicated by the phone reseting the CWM to default recovery mode and I'm having to reinstall CWM over and over.. other times the ROM simple don't boot, get stuck in the Vibrant logo. This is insane, what are the restrictions for restoring a rom with CWM?? shouldn't it erase everything so no incompatibility is left? Is there differences in restoring with version 2 of CWM or a 3 version? I don't even know exactly what OS version some of the roms are, so that I could try upgrade the phone to that version first and then applying the restore. Nothing works, I'm very pissed.