[japper88]

As the other two posters said, you should do that "flash dance"

Personally I do this every time i flash to a new rom:
Flash to stock (your carrier's stock rom)
hard reset the stock rom (clean storage via settings is good enough)
flash to the new rom you want
hard reset the new rom (clean storage via settings is good enough)
now you should be all set

if you want to be really thorough, you can hard reset (clean storage via settings) on your current rom before flashing to stock, but I usually skip that step.

I know this sounds time consuming, but it's really only an extra 10 mins, and should solve you tons of headaches.