Doing a fetch or Pull in Visual Studio stopped working today

[Julia Allchin]

Today all users can no longer do a fetch or pull in Visual Studio
It was working fine yesterday

Today you choose Fetch and it pops up to logon (didn't yesterday) so enter them and Continue
and get 

Failed to fetch from the remote repository. See the Output windows for more details

There are no further details in output window

Tried everything and cannot get it to work.