To fix the problem that dvd drives are not recognized in Windows 7 permanently do the following:
1. Press Windows R, type regedit and press enter.
2. Open the Registry key
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.
If you need more assistance on this, contact http://www.247techies.com/
for immediate Microsoft tech support