Can't view site after login

After loging in the site goes blank.  All white screen.  I reload the page and it tries to load but then goes all white again.  This happens repeatedly until I get an error message that reads, "Citibank is not availbale."  The same thing when I try to sign on with my phone app. error reads, "sorry we are having some temporary delays.  please try again later"  All day today....