Weird GUI Glitch

What’s the problem?:
-When trying to revise an existent car, I get this error:

And then this will happen:

When it started appearing?:
-I don’t really remember, I think that yesterday at night I was fiddleing with the files on the game’s folder found in My Documents and then I got the glitch. Didn’t tried to fix it and I shut down my PC because it was late.
Today, when I got back to the game, I got the glitch again, so what I did was to make a separate backup folder with all the cars and engines I’ve made to date, and then put the only files I was going to need (just a car), in an effort to fix it, but it didn’t work.

If you need the link to the only car I have in my game’s folder there you have (made by NormanVauxhall): download/file.php?id=12739
I highly doubt the car has something to do with it, but just in case…

That might be an issue with mods? Do you have the same mods installed as he used for making this car?