I happened to notice LOADOUT does not work either. All my other games Ive tried seem to work. Maybe there is a connection there?

I believe I jumped to rank 5 only but, it did occur as I was ranking up and left the game.

Ok, so after seeing some people stating it was now working, I decided to give it a try. Since I used to have novid and dxlevel9.5 on my launch (but deleted it when I saw this might be the issue) Tf2 brought me to the main menu.
All Matchmaking (Comp, Casual and MvM) were all grayed out. Since Steam was down, I figured it was just on their end.
I swapped to my alt, which still ran everything perfectly.
Went back to my main and poof..... getting the old error back again now

So, still not working.....no joy in TF2-town
Guess I'll just smurf on my alt till they get around to fixing this.

Deleted almost 100 recent new files, un-synched with cloud, still get the error. I can log into my wifes account from the same computer and have no issues playing on that acct. Something got borked during the night as I was playing just fine then.