That did indeed correct the problem. Wow! Thank you! I've been having a terrible time with this! Incidentally, the analogous fix in Thumbs9.vconfig produced menus in Version 9. I lost those so immediately that I wasn't quite sure they were ever there.
Now as cspitser asks, how does this happen?
Twice, obviously, one in each version. Originally in 9. Some time later in 8.
For me (Windows 7) the file's in
C:\Users\USERNAME\AppData\Roaming\ThumbsPlus