WTF My Left 4 Dead Steam!?!?!?!?

Ok so I bought Left 4 dead on.. Monday. This week. And I have yet to finish downloading cuz I was downloading Portal and TF2 which if I have more than 1 or 2 games downloading it takes longer to download the others. So I believe Left 4 Dead finished downloading.. but now it's UPDATING! And now the updating won't get ANYWHERE! Its still at 0% for like 3 days! It was at 10% but I accidentally double clicked it and then it started to 'launch' and then it reverted back to 0%. WTF?! PLeas help me.WTF My Left 4 Dead Steam!?!?!?!?
Just now at 3%.. then back to 0%!!!!!!!!!!!!!!!1WTF My Left 4 Dead Steam!?!?!?!?
Did you ever consider stopping the other downloads, or logging off the computer for a few hours?
I've had the same problem before. I simply pause the download, then I resume it. Usually that solves the problem for me.
That.

And make sure you aren't playing any other Steam games, that stops the download.
my half ep 2 is updating and its been at 0 percent for like 2 days
Had the same problem. One way I did to assure it was downloading was trying to stream youtube videos on my ipod touch.Another way was to start the game, and it gives you a countdown to when the game will start up for you. As long as the timer goes down, you're fine.
Im not playing any games...UGH! HELP!
one thing that i find works is pausing all downloads and then trying to launch the game from the steam window, a updater screen should show up and for me the download always works from there...
Stop the updating, close steam, restart your computer. Then turn off firewalls, start steam, resume updating, and don't do anything else with your computer. If you live at home/have roommates, tell them to get off their computers so you can have all the bandwidth. It's vital you don't open any web browsers since your firewalls are off. Just let it update -maybe turn the monitor off so it's not too tempting to do other things with the computer. And don't update/download other steam things either.
Or just try and reinstall the game.. that fixed it for me with Portal..