User Can't Log Into TEST - Creds Just Clear Out - No Error Message

Summary

After P2T one user can't log into TEST environment. After clicking "Sign In" his userid/pw just get cleared out.

Content

We have one user who is unable to log into our TEST environment after P2T refresh.  After he enters his userid/pw and clicks "Sign In" his credentials are immediately cleared out and no message given.  This only happens with this one user.  Other users are either able to log in successfully or they receive "Authentication Failed" message as you would expect.

Has anyone else experienced this?  I don't see anything usual about his user set up.  I've had him try different browsers and even different PCs.  Processes "Retrieve Latest LDAP Changes" and "Import User and Role Application Security Data" are running every 6 hours.