[DoubleK]

Issue can occur due to corrupted Windows temporary files or if Norton Antivirus (NAV) feature try's to scan floppy drive for virus during shutdown. In order to resolve this issue, I suggest you follow the steps provided below:

-- Start Norton Antivirus (NAV) 2007
-- Select Auto protect under "Settings"
-- Select configure
-- Under real-time Protection,Select General settings.
-- In the right pane, uncheck "Scan floppy disk in A: for boot viruses when shutting down."
-- Click ok
-- Restart the computer.

Good old Norton NIS

It seems that uninstalling Norton will not rid you of the problem either.

It appears if the above does not work you will have to uninstall Norton360, reinstall XP SP2

At that point unless your capable and confident going on goose chases I would live with the issue.