After a "Log Out" trying to login:
With IE8 it fills the username but leaves the password blank.
With Opera and FF it leaves the username and the password blank.
Only vB4.0.3 at vbulletin.com/forum and mydomain.com/testvb.

Anyone else using Norton 360 version 4 having the same result?

Edit: Confirmed as a low-priority bug in the bug tracker.