I stupidly decided to opt-in to the Steam Beta client today. WHAT A MISTAKE!
After applying a patch and restarting Steam I was greated with the following error:
"Error...steam.exe (main exception): " yada, yada, yada but the best part is that the error was Error 1 or 0 "unknown error".
Well after about 45 minutes I got things working again.
I used the repair option given from the installer on my original Orang Box DVDs. Then, I deleted the Registry Keys "beta" and everything under "Users" at the following location:
After that Steam started, updated, and I simply logged in again. Bingo!