Don't try to bypass the installer checks, while the game may seem to be working, it will inevitably CTD later on. Also, as soon as the installer notifies you of a corrupt file, all possible subsequent errors will be supressed.
I'll remind you of MD5 Mate and the process required to check your downloaded GWX files. Check it out here -
http://www.thegreywolves.com/downloads/
If your codes do not match re-download, from a different source, the part with the error.
Check the GWX parts and tell us which part is corrupt.