Perforce is awesome, but it has one giant brain fart problem. It corrupts unicode files on the client based on the typemap. It looks like the nvTextureTools .rc files are all corrupted due to an invalid typemap of your p4 server. At least that’s what it looks like when this same sort of thing happens to me.
Please take a look at all of the .rc files off of this root folder: “Engine\Source\ThirdParty\nvTextureTools\nvTextureTools-2.0.6\src\project\vc11”. They are not valid .rc files.