Have you tried resetting permissions on the Members directory, and rebuilding the Member Stat files?
I find that if I run into a problem, and I get an error message, and I follow what the UBB tells me to do, it works.
Personally...following the directions contained in the "upgrade.txt" file with the 6.1 (et.al.) upgrades to the UBB, I had no problems what-so-ever upgrading...I had UBB 6.0...did NOT use any of the Beta releases, and went from 6.0 to 6.1, and then to 126.96.36.199. almost immediately with no problems...follow the directions to the letter and you shouldn't have any problems.
MSgt Jim Thede
USAF PararescueUSAF Special Tactics
"These things we do that others may live"