Second log on on XP fails

I have Win XP (Home) SP2 set up for 4 user accounts. Recently after any account has logged on then off, a second (or same) account logging on has frozen. Pressing Ctrl, Alt & Del makes the “Loading your personal settings” message appear, but it doesn’t go any further. I have tried reverting to a Restore point before the problem, disabled all start up items apart from AV and firewall and checked the Event log for anything to suggest a problem.
I have recently installed Net Nanny 5, the MS Malicious software removal tool and AVG Free 7.0. I’ve uninstalled all of these in turn without success.

Help!!