Dilyn

I got my computer back after my long vacation, hoping to fire up some L4D. Apparently, Steam decided to mess with my mind.

Steam will not install. I have tried, and every time it says that I don't have permission to install into the directory (C:\program files\Steam). The account that I'm using is the administrator account, so I have the right permissions to install anything. I've installed several other programs into my program files directory, and they work just fine. Steam is the only one giving me problems. Now I can't play any of my Steam games (TF2 and L4D).
I've tried to run the installer as administrator, I've tried to change permissions in all sorts of folders for my account, etc. and nothing has worked. I tried to boot into the Admin account, but every time I log in it just gives me a blue wallpaper (think Windows 98) with no icons or taskbar or anything. I can use ctrl+alt+delete, though.

Any help would be MUCH appreciated. I need my L4D fix!!!