incorrect user name or password error at start up

Hi,
When I start my computer I get a Login Error that says 'Incorrect username
or password' and an OK button only. If I leave it or click on the OK button
a few seconds later the computer reboots (only the once) and then works fine
for the rest of the day. This happens every time I shut the computer down
and restart. I can't see anything relevant in the event viewer logs.


.