Steam Won't Start...

[Dog--]

I click on it, it appears in processes tab in task manager, but never shows up or anything..

I tried clicking it's shortcut, it's main .exe, and even tried letting it run at start-up, and it just stays in processes with 15,483KB mem usage. Never changes... I really want to replay HL2 and finish downloading Quake.. I had it running 2 days ago, didn't run it yesterday (I was too busy), tried to start it today, and it does this...

Help?

 

[Mahalis]

Delete your clientregistry.blob and restart Steam. If that still doesn't work, delete all the DLLs in the Steam folder - should force it to download a clean copy.