CD-ROM drive or DVD-ROM drive appears to be missing after you install Windows XP
Method 1: Remove the registry entry
1 Click Start, and then click Run.
2 In the Open box, type regedit, and then click OK.
3 Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE/System/CurrentControlSet/Control/Class/{4d36e965-e325-11ce-bfc1-08002be10318}
4 On the File menu, click Export.
5 In the File name box, type savedkey, and then click Save.
6 Click the REG_MULTI_SZ data type UpperFilters, and then click Delete on the Edit menu. When you are prompted to confirm the deletion, click
Note If this data type is missing, go to Method 2.
7 Click the REG_MULTI_SZ data type LowerFilters, and then click Delete on the Edit menu. When you are prompted to confirm the deletion, click Yes.
8 Quit Registry Editor, and then restart the computer.
Method 2: Replace the existing driver
1 Click Start, and then click Control Panel.
2 If Control Panel is in Category view, click Performance and Maintenance, and then click System.

If Control Panel is in Classic view, double-click System.
3 On the Hardware tab, click Device Manager.
4 Click the drive with the question mark next to it.
5 On the Action menu, click Uninstall. When you are prompted to confirm the removal, click OK.
6 Repeat steps 4 through 5 for any other drives with question marks.
7 On the Action menu, click Scan for hardware changes.

- srikanth dhanwada