I'm trying to start doing lobbies. Yesterday was my first day. I got into one lobby, but the game was disbanded due to dropouts. After that I tried joining a few others and TF2 wouldn't open at all, neither would my other Steam games. It took me all day to get TF2 to work. I updated windows, my drivers, I put in a ticket with Steam and they told me to refresh my Steam files and verify the game files. I finally was able to play pubs last night. Today I just tried to go into a lobby, but the same thing is happening and now I'm going to have to mess with all the files again and hope that works.
One thing to mention: when the game starts, I'm not receiving the popups to join Mumble or the game. I did for the first lobby I joined, but haven't since then. Since I can't even get TF2 to open to manually enter the lobby, I'm wondering if this is connected with the bigger issue I'm having.
Thanks for the help!