I read a lot about phones needing the "latest version of clockwork mod" when flashing new ROMs. However, I don't really know where and how to get and install it. I found this page: ClockworkMod ROM Manager - Recoveries but am not sure what to do.
ROM Manager has a spot that will check what veesion you have and can even upgrade right from there. In settings you want to check Erase recovery first.
You can use ROM manager to upgrade to the 5.0.2.0 version oc CWM. or you can download the PB31IMG.zip here. Recoveries | PvilleComp's
and flash it in HBOOT.
ROM manager is easier but be sure to go to Menu -> Settings and select Erase Recovery before updating. It will save you from having to do it again.
Of course if you already have 5.0.2.0 then there is no need to do this.