Users revert back after usergroup change
 

Hello*

I seem to be having a bit of trouble with changing my forum users' usergroups.. On certain members* the change doesn't stay. What I'm trying to do is move the users into a Donators usergroup after I've confirmed receiving a payment in paypal* but for two of my users* after switching them into the Donators group* they repeatedly get kicked back into the Registered Users group after about 5-10 minutes. I've tried doing the repair & optimize tables thing* but it didn't do any good.

Does anyone know what could be causing this?

Thanks!