You might have download iTunes or ROXIO or some other program that has messed with the Registry.
Try this fix direct from Microsoft:
To resolve this problem, remove the affected filter drivers. To do this, follow these steps:
1. Click Start
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Start button, type regedit in the Start Search box, and then click regedit in the Programs list.
If you are prompted for an administrator password or confirmation, type your password, or click Continue.
2. Locate, and then click the following registry subkey:
Caution There can be many instances of the registry subkey that is mentioned in step 2. You must make sure that you are in the appropriate registry subkey before modifying the UpperFilters and the LowerFilters values. To verify that you are in the appropriate registry subkey, make sure that the Default data value is DVD/CD-ROM and the Class data value is CDROM.
3. In the right pane, right-click UpperFilters, and then click Delete.
4. Click Yes to confirm the removal of the UpperFilters registry entry.
5. In the right pane, right-click LowerFilters, and then click Delete.
6. Click Yes to confirm the removal of the LowerFilters registry entry.
7. Exit Registry Editor, and then restart the computer.
The system will automatically rebuild the registry records when you restart your computer.