GreySucksThere's an incredibly small chance that you have something malicious on your computer, although you should check anyways. Be sure to run anti-virus software if you have any, just to be safe.
If you haven't been VAC banned, then you should be fine. Restart your Steam, computer, etc. Also be sure you aren't running the game with any launch options that could cause issues (such as -insecure). You can also try removing your custom folder, as there may be some sort of addon you have that is causing issues. If you're still unable to connect to VAC-secure servers, try reinstalling TF2 and/or Steam itself.
Hope this helps a bit, let me know if you have any luck!
I restarted my pc and rejoined an mge server - seems fine for now
What causes the VAC problems btw?