Most probably you need to make a factory-reset if you change the rom.
Sometimes a "Clear Dalvik-Cache" works too but the prefered way is a factory reset...
If i change my rom from Rom X to ROm Y (another rom, not just a new version) then i always do a factory-reset AND Clear Dalvik Cache.
If i just update a rom from version X to a newer one (but the SAME rom)) then i try first JUST clearing the dalvik cache....