Or you can rename (or delete) ClientRegistry.blob and AppUpdateStats.blob in the steam folder. Otherwise delete SteamUI.dll in the Steam folder. ONE OF THESE SOLUTIONS WILL WORK! Hang in there mate! :)
Well man, if you must.. Uninstall steam and reinstall. If you don't want to do that then just keep trying. Maybe Restart your PC and internet and if that doesn't work then run steam as Administator. (right click + propitarys) Hope it helps mate, I don't want to lose you. :(
.---oOO-- (_)-----.
╔═════════════════╗
║......... [---darknova---]..........║
╚═════════════════╝
'--------------------oOO
...........|__|__|
............. || ||
........ ooO Ooo
/▌
/ \