"Please exit Steam and go to the folder called C:\Program Files\Steam\ (this is the default location for a Steam installation - if you set a different installation directory, you will need to browse to it).
Delete all of the contents of this folder except:
The Steamapps folder and Steam.exe (If 'exe' is not visible, look for the black and white Steam icon)
Restart your computer.
Then, you will need to launch Steam.exe from within the Steam installation folder, and not from a pre-existing shortcut.
With Steam running, re-test the original issue.
Note: This process will not affect your currently installed games."