You just have to delete pctrlchk.dll in the game folder (where xrEngine.exe is located)

It worked perfectly for me ! :) Enjoy !

had the same issue, setting xrengine to run as admin fixed it

I had the same issue that the game starts or does not start randomly. Searching for a solution stumbled over the OpenXray-Solution (on reddit though)
Worked but as said the savegames do not work anymore and somehow the water effects looked strange.
Then I found this thread and I tried Heihatchi solution and just remoced the pctrlchk.dll
And as it seems that was the troublemaker. So a big thank you to Heihatchi!

So my suggestion is:
1. Try to start the game after removing the pctrlchk.dll file (you don't need it aynway!)
2. If that doesn't work try to start the game by using the compatibility mode
3. If 1. and 2. did not work try to uset he OpenXray-Solution

Note: Reinstall the game before you try 3.

Update on my previous post. As I said deleting the file pctrlchk.dll made the game run, for me (no problems what so ever!)
BUT! If you start GOG Galaxy the game will "update" the game which basically will reinstall the file.
So right klick the game in you GOG Galaxy-Game library and uncheck auto update (the game is outdated anyway so there will be no real updates, in the first place!)
If the "update happened" you have to remove the file pctrlchk.dll again and maybe also edit the file fsgame.ltx
But just in case an error message involving this file pops up. If so, open it with the editor and delete all lines that got dublicated, save the file.
The game should now start nornaly, again.

That's the answer :) Open X-Ray engine runs terribly on my PC so not a solution for me. Anomaly & Lost Alpha which are graphically far more intensive run great.

Q-6

Thank you, Master!!!!!!! This worked for me, when none of the other solutions did (I did not try OpenXray)...

So how did someone figure out that this dll was the issue???