Umm, which drive are you talking about? A DVD/CD drive? Or a Hard Disk Partition? Because if it's the latter, you might have a virus.
If it's about a DVD/CD drive, here's how to disable autorun altogether on Windows XP:-
1>Go to Start>Run> type in "gpedit.msc" without the quotes and press enter.
2>Expand Administrative templates by clicking on the little plus/arrow next to it.
3>In the bunch of folders that dropped down, find out "System" and click on it.
4>In the right side pane, find out the entry called Turn off Autoplay and double click it.
5>Check the "Enabled" radio button. Select "All drives" from the drop down list below the radio button. Click on OK.
6>Reboot the PC.