Computer hangs on Windows XP Log on - Any Ideas?

[Grey Fox]

I have this computer, it seems to hang on the windows xp log on scrreen (2 shades of blue & Microsoft Windows XP logo.

It's not frozen, keyboard & mouse works, just no where to click.

Safe mode does the same thing.

Any ideas what it could be?

[Scipio]

Sounds like antivirus start-up scan.