Sorry for the delayed response. Had an important meeting at work. I would try a file verification first, and then reboot then start steam then game guru. This normally takes care of those kind of errors.
Since it appeared that a system file is the culprit here.
Let me know if this works for you.
Also if on a win 10 system , maybe try setting all the executables in the Game Guru folder to run as admin.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit, Screen resolution 1680 x 1050.