I have never heard of that happening, I would reset Steam.
1/ Turn off Steamguard if you are using it.
2/ Go to Steam install folder and delete everything EXCEPT steam.exe and the steamapps folder
3/ Reboot your PC
4/ Browse to the Steam install folder and run steam.exe
You will have to enter your username and password, and everything will setup without losing your games. If you didn't switch off Steamguard, then when trying to log in, you will have to wait for a security email to arrive with a special code in it.