Here is a steam discussion I started about the issues and any fixes the community has found so far:

http://steamcommunity.com/app/620/discu ... 384117529/

HAMMER AND P2 WORK

Edit: I now realize this is a 1 story building

josepezdj wrote:
I keep having the same issue: Portal2 refuses to close! No matter what I'm doing, it crashes when I try to leave a workshop map from playing, also when I'm at the main menu and want to quit.... Isn't anyone else experiencing this issue?

Until they fix this problem, write "quit" in the developer console.

yishbarr wrote:
josepezdj wrote:

I keep having the same issue: Portal2 refuses to close! No matter what I'm doing, it crashes when I try to leave a workshop map from playing, also when I'm at the main menu and want to quit.... Isn't anyone else experiencing this issue?

Until they fix this problem, write "quit" in the developer console.

Damn, Yishbarr! THANK YOU!

CamBen wrote:
Wait, I managed to fix it It was a bit more of a hassle for me since one of my computers has hammer installed under Program Files (x86) and the one that needed fixing was installed under Program Files, so I had to do a bunch of annoying folder creation and messing around with gameinfo.txt files, but here's the good part for all of you guys:

Since most of you run off a windows 7/8 now probably, here's a fix for hammer. Replace your Common/Portal 2/Bin/ folder with this:

Is working perfectly now.
Thank you.