MD5 Failing and ban

This is what happened:
I joined the facepunch fretta server, and I was only playing for about 18 seconds when I was kicked from the server because of MD5 failing or something like that. So I waited for another empty slot on the server, and I rejoined only to find that my steamID was banned from the server.

Does anybody know what happened?

on some server if you have any client side mod or files it my kick you or ban you. this may be the case if you have gore mod or something. you have to delete the mod to fix this!
ps. not shure if this is the case btw