After patching, the small windowed menu pops up. Hitting start states this:
The launcher is unable to start game. Please be sure you have the launcher in the installation directory PSOBB and that Psobb.exe exists there.
If you cant find Psobb.exe your antivirus might have quarantined it.
In my Ultima PSOBB folder under Local Disk (C:), here is the list of items in them:
Bmp
data
log
teamflag
Launcher
psobb.dll
psobb.exe
unis000
Unis000
However, this symbol is next to Psobb.exe