Quote from UnknownTBeast on October 4, 2011, 7:14 pm

I am unable to start Portal 2, or the Portal 2 Authoring Tools - Beta

I installed yesterday the authoring tools for p2, and made a test map. After saving it, p2 would not load the map. After a little research I found that I should check the game integrity. I did that, it found a few issues, and redownloaded the corrupt files. P2 was able to open the map, and I was able to relaunch the authoring program.

I turned off my computer when I left the house this morning and when I got back I was unable to launch the authoring program. After a few attempts, nothing, so I restarted Steam and nothing, then my computer, nothing. So I did the integrity test for both p2 and the authoring tool and it found problems. It fixed it for both P2 and the authoring tool. Neither program would launch.

I've tried repairing Steam with SteamService.exe /repair and deleting that .blob file to redownload Steam files, and uninstalling Steam, clearing out the register of old keys, then reinstalling, then had to reinstall the game/tool and I still can't launch them.

I confirmed that it is only P2 and the Authoring tool that are having the problem. Portal 1 and Crysis Wars will launch.

Sent this to Steam support, but forum may be more helpful since I believe the problem lies with the Authoring tool.