I lost the internet for a week, and during that entire week I managed to get Steam to login to Offline Mode once, and during that time I couldent run anything. HL2, CS:S, HL1, DOD:S, Hammer.. nothing. Every time I tried to run them I got a "This game is not availible in Offline Mode" error. Whats the point of having an Offline Mode when nothing can run with it!? Rediculous.
Then after I tried re-logging into Offline Mode, Steam would crash with some error of being offline..
Needless to say, it was a very unproductive week..