Last night my daughter's PC was fully functional and this am it boots
up but email, and most programs, including antivirus and antispyware
utilities will not open.

For some reason Norton and SpySweeper wll not open and both tell me to
reactivate in order to use.

Yahoo Messenger still works as does Microsoft Messenger.

I have tried the F8 procedure during bootup and have selected both
return to last operation windows and restart in normal mode but
nothing I have done seems to get me back to a working condition.

System Restore does not work either. I ran MicroTrends virus scan and
nothing was found.

Does anyone have any ideas or suggestions on what has happened?

TIA

Frank