I've installed Patrician 3 as Administrator under XP Pro. Now it will only *run* as Administrator. When I try to run it as a regular user I get the error message about running p2setup.exe. There's no p2setup.exe installed but running the p3setup.exe that does exist doesn't fix the problem.
How do I get this game to run as a regular user?
Another user mentioned that they received a reg file from GOG support for this game. Can I get a copy of that reg file? It might do the trick.

I solved my own problem. Had to figure out the original publisher's name in order to find the right key in the registry. The key that needed to be modified is:
HKEY_LOCAL_MACHINE/SOFTWARE/Ascaron/Patrizer 2
If you give read and write permissions to whatever user you want to run as, the game runs fine.
A reg file for this location looks like:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Ascaron]
[HKEY_LOCAL_MACHINE\SOFTWARE\Ascaron\Patrizier 2]
"800x600x16"="OK"
"800x600x32"="OK"
"1024x768x16"="OK"
"1024x768x32"="OK"
"1280x1024x16"="OK"
"1280x1024x32"="OK"
"Adapter"="Primary Display Driver - display"

Great tip!