Close Game guru and Clear your browser cache files. Restart the browser. Log in to the store page with the account your made the purchase with. either TGC or steam wallet.
Open GameGuru, and when the editor comes up, Just press file download store items.
Should scan our machine for installed media and then tell you how many files will be downloaded. Press download. Wait 30 seconds, if nothing happens press download one more time.
This should start the download process.
Hopefully this has not locked the account yet. If you get the same error then I will need you to press the green Help Button to the lower right of this window. Provide as much info as you can. the will need your TGC account name, and your email address, and your Steam Profile name that you have linked.
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