MDL/TF2 Crashing, and not working.

Hey there, tf2 keeps crashing. I am a skinner(how else do i say it?) and whenever I try to make my own server, or get into another server with my weapons, it crashes on me!
Also, whenever I try to look into the mdl files, all they say is nul (null). I really don’t know why all my .mdls are like that… please help!

I deleted all my skins and its back online…
Very weird.