I was playing on RND zombie server normally like everyday. I left the game and saw that GMOD was updating like (250mb) When it finished, I tried to connect again and I got this message:

Connecting to 173.60.110.96:27025...
Invalid Steam key size.

I can't connect to any GMOD server now (Only servers that has the "Sandbox" thingy)

Here is what I have tried:
- Restarted steam.
- Restarted PC.
- Verified integrity of game cache...
- Deleted Engine and some other dll file after backing them up.
- Insulted valve for one minute long.

All that didn't work, I would still get that message. If you know something then help please.

Thanks!