XP Shutdown

[Michael R]

I am having a problem on XP (Home) shutdown screen.

When I hit start, then turn off computer, i get the three icons, turn off,
restart or standby. The only one that works is standby.

To physically shut down, I have to go in to the standby screen, then use the
turn off icon.

I have tried various patches, which don't work. I have lastest virus
definitions, they fail to find any viruses.

Any Suggestions?