How common is it to have an abnormal pap 6 months following a colposcopy freezing?

Quite common. The freezing or cryotherapy does not get rid of the virus which caused the abnormal cells. It only gets rid of the abnormal cells. If the virus that caused the cellular abnormalties (hpv) persists in your system, it can cause cellular irregularity (dysplasia) at any time. Just make sure you keep up with the pap smear schedule recommended by your gyn.