We see this kind of problem fairly frequently, usually after someone has installed additional CD/DVD burning software to the system, when it already has some. The first symptom people notice is that, suddenly, CD/DVDs won't play when inserted into the drive like they used to, OR, the new CD-burning software can't find the optical drive.

When that happens, Confirm that there are no driver related issues (check Hardware Manager, if you see a Yellow Triangle with an exclamation point, right click and uninstall the driver then reboot - it will be re-detected automatically.) then check explorer to see if there is no drive letter, and then confirm that the disk can be read by another PC. You could also try removing the recently added CD-burning software.

If none of the preceding steps resolved the issue, then use this simple registry fix: if the filters shown in the steps below are there, remove them and reboot - POP. (straight from Microsoft - all rights reserved, etc. - Paraphrased, remunerated, and clarified.):

1. Click Start button (In XP then run),
2. In Windows Vista/7, Type regedit in the Start Search box, and then click regedit in the Programs list. (In XP, type regedit in the run box and press enter)

User Account Control permission - If you are prompted for an administrator password or confirmation, type your password, or click Continue.

3. Locate, and then click the following registry subkey:
   

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
   

   Caution: There can be many instances of the registry subkey that is mentioned in step 3. You must make sure that you are in the appropriate registry sub-key before modifying the UpperFilters and the LowerFilters values. To verify that you are in the appropriate registry sub-key, make sure that the Default data value is DVD/CD-ROM and the Class data value is CDROM.

4. In the right pane, if you have UpperFilters, right-click UpperFilters, and then click Delete.
5. Click Yes to confirm the removal of the UpperFilters registry entry.
6. In the right pane, if you have LowerFilters, right-click LowerFilters, and then click Delete.
7. Click Yes to confirm the removal of the LowerFilters registry entry.
8. Exit Registry Editor, and then restart the computer.

Note After you remove the UpperFilters registry entry and the LowerFilters registry entry, you may lose functionality in certain programs such as CD recording programs. In this scenario, you must reinstall any affected programs. If the problem recurs, contact the program vendor to determine whether an update is available for the program.