Well, if you Donator rank depends on rights, this is how you fix it.
Where ever the login message is generated from, there should be two thing
One indicating the donator rank, and one should be like > 0. Change > 0 to = 0.
That should probably fix the problem, if thats it. :\ Kind of hard to explain, so post the file with the login message coding and I'll do it for ya.