sounds like your Anti virus is blocking files. exclude all the GG exe's and also there is the temp folder in the yourprofile\appdata\tamp folder. exclude this folder and try again.
If this persists, then please verify in the steam interface the file for GameGuru. In the library section RMB on gameGuru Icon and choose properties. 3rd tab verify files option button. it will tell you how many files are missing and que them for update.
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