I have a Toshiba laptop (A105-S4211) with a missing optical drive. I followed the instructions for removing upperfilters and lower filters and voila, the drive reappeared after I restarted the computer. On the next restart it was gone again. I opened the registry and viewed the settings again to make sure I had followed it properly and I did. Next reboot, there it was. Puzzling. After further reading I found other references to similar problems and tried those solutions such as removing and reinstalling any CD/DVD applications (Sonic RecordNow!, WinDVD, etc..) and reinstalling them and every time I would make a significant change to the computer the optical drive would reappear but on the next restart it would be missing again. I then remove the device from the device manager and again it reappeared after windows redetected it and reinstall it. Sure enough on the next restart it's gone again. I also discovered that even when the CD/DVD drive is present Sonic RecordNow says it cannot find any compatible devices. Lastly, just to make sure you're aware of this, I did test to make sure when the drive is visible in My Computer that it reads CD's and it does so I don't believe the drive has malfunctioned.