The installer of ThumbsPlus v9 SP2 beta3 has a strange issue. Although the main file of version 3943 is Thumbs9.exe, the installer also installs file Thumbs.exe, which is of older version 9.0sp1b73937. This causes a strange behavior: when I run program with a shortcut, which indeed leads to Thumbs9.exe, everything is normal. But when I click database file, which was set to open with Thumbs.exe, an older version (from the same directory) opens, which causes ThumbsPlus to signal continuously about the update. Took me some time to figure out the reason. I'm 100% sure the uninstallation clears all the exe files from the system, and there were no other Thumbs plus versions in other directories installed on my machine. Thumbs.exe is clearly installed by the installer of the newer version "Thumbs9.exe".
I think, the old version should be removed from the installation.