I think Flag4 has hit it on the noggin!
The best thing (all though not your favorite thing I bet!) to do is to get rid of everything!!
Keep all the mods that you've downloaded in their zipped up or downloaded file instance, but uninstall everyone of them, and SH3 itself.
Then go hunting on the hard drive and KILL anything you see that is either Mod or SH3 related.
Then start with a full, clean reinstall of SH3, then add your mods, I suggest you add them one by one, starting with GWX first, and SH3 commander last.
Then give it a good old try again.
Good luck!
