Null Sid Security Group problem in AD

We have 3 Credit Union Branches, the 2 remote branches that run across a T-1 line are having problems on the domain where the Local Group Policy is not applied because of the Null Sid security group after running gpresults. I did some research & removing the computer from the domain & then adding it again solves the problem temporarily. I have only found this problem on workstations at the remote locations, & it’s unfortunetly quite common, anyone come across a problem like this and how it might be solved?

I’m running 2 DC on a mixed 2000/2003 enviroment with the 2003 DC holding the FSMO roles