If your computer reboots from just trying to access D it could be a virus-Norton will boot from a cd in dos and you can scan d: drive from that. There is another post I left-startup\system\advanced\startup and recovery\disable restart-When this is left on windows xp will restart the machine on many errors. memory errors and program errors will restart your machine-by disabling this feature you can possibly trouble shoot the actual trouble. id also try scandisking d: