I get this recently after joining or well, TRYING to join in on [BB]Classic:[attachment=0:3ccij0co]classic.JPG[/attachment:3ccij0co] I'm guessing I need to download a noclip plugin or something.. but I'd rather not do anything without confirming on what I should do to fix this situation. On Task Manager after launching Garry's Mod connecting to BB Classic, the Commit Charge is 833M/3481M max, not sure if that will change anything though. EDIT- I'm mainly worried about that thing near the top right corner saying Lua plugin missing etc etc.
Funny thing about it; I joined in on Darkland Fortwars for some DMing fun and the end score was 0:00 Blue and 0:04 Red on Fortwars: Reloaded. I was on red team but it was still fun, I got ticked off because some player kept giving blue the ball for no reason which later explained as, "It wasn't assualt?! Woops...." I quit and joined in on Classic and for some reason it worked then and no other time when I tried joining... So... I guess it's considered fix, I just have to join Fortwars then move onto Classic or something I guess...
Reinstall Gmod. What you have is i believe a few addons colliding judging from the player select menu.