I'm getting a "steam validation rejected" message when connecting to the server. Was having no problems before the last update. I've been on a fair bit lately and had no problems until now and can still connect to (some) other servers. A quick google indicates it might be a server-related issue, might need a reboot?
Seems a bit quiet out there in TF2 land, so can only assume there's quite a few people/servers having the same problem.
If I'm wrong and it's just my steam file s corrupted (yet again), apologies.

looks like the server is locked mate, probably some secret hh stuff going on

You need to update steam.