Can't login anymore with GUI

[Duke Normandin]

Hello list ...

All of a sudden, for no apparent reason, I cannot login anymore using
the usual xfce login GUI. I have to start Xubuntu in recovery more;
then select the last entry in the menu "net root" or something; then
login with my usual login name at the CLI, the do "startx". Then
everything is as normal. How can I fix this - and why did it happen in
the first place? TIA...

-- 
Duke