Windows Vista Home + iTunes = no DVD drives

Question

I am a long time iTunes user, and have been having an issue with iTunes for the last little while. When I install iTunes (I'm on Windows Vista 32 bit, by the way), after the required restart, my DVD drives' icons disappear (I have 2 of them). I can see the DVD drives in the Device Manager, and they say they cannot start. The only I think I've had these problems since about iTunes 7.0, but I don't burn CDs that often, so I've really not felt too bad about it, except that my wife would like to do so. I've done the registry change where you remove the upper and lower filters, which corrects the drive issue, but then presents the seemingly inevitable Registry issue dialog box, without the option to burn CDs. Here are the steps I've done thus far to try to get my computer and iTunes to play nicely:
1. Tried reenabling the UpperFilter for GearAspiWDM as described here: http://docs.info.apple.com/article.html?artnum=305422
2. Tried downloading new GEAR drivers from their website.
3. Tried uninstalling Quicktime, and then installing it separately.
4. Uninstalled my other music service software (SonicStage), and then reinstalling iTunes.
5. Completely uninstalled iTunes, and then reinstalled it (a couple of iTunes versions ago).
6. Tried uninstalling the non-functioning DVD drives in the device manager, and then scanning for hardware changes. When the UpperFilter was still present, this part failed. It passed after I removed the UpperFilter registry entry.
Please help!
Edit: Here's my most recent diagnostic info (with Drives, without UpperFilters).
Microsoft Windows Vista Home Edition (Build 6000)
MICRO-STAR INC. MS-6728
iTunes 7.6.0.29
QuickTime 7.4
CD Driver 2.0.6.1
CD Driver DLL 2.0.6.2
Apple Mobile Device 1.1.3.26
iTunes Serial Number 20D6EAF059AB94B4
Current user is not an administrator.
The current local date and time is 2008-01-15 18:41:21.
iTunes is not running in safe mode.
Video Display Information
ATI Technologies Inc., Radeon X1600/X1650 Series
ATI Technologies Inc., Radeon X1600/1650 Series Secondary
** External Plug-ins Information **
Plug-in Name: Last.fm iTunes plugin
Plug-in Loaded: Yes
Plug-in Version: 0.0.13
Plug-in File Version: 2.0.13.0
Plug-in Path: C:\Program Files\iTunes\Plug-ins\itw_scrobbler.dll
** CD/DVD Drive Tests **
Failed loading CD / DVD drives, error -43. Try doing a repair install on iTunes from the "Add or Remove Programs" control panel.

Answer 1

Update:
I tried what the diagnostic told me to do, and repaired the installation. I was able to burn a CD in iTunes, but after I restarted, the drives have disappeared again! Here's the diagnostic info now:
Microsoft Windows Vista Home Edition (Build 6000)
MICRO-STAR INC. MS-6728
iTunes 7.6.0.29
QuickTime 7.4
CD Driver 2.0.6.1
CD Driver DLL 2.0.6.2
Apple Mobile Device 1.1.3.26
iTunes Serial Number 20D6EAF059AB94B4
Current user is not an administrator.
The current local date and time is 2008-01-15 19:09:32.
iTunes is not running in safe mode.
Video Display Information
ATI Technologies Inc., Radeon X1600/X1650 Series
ATI Technologies Inc., Radeon X1600/1650 Series Secondary
** External Plug-ins Information **
Plug-in Name: Last.fm iTunes plugin
Plug-in Loaded: Yes
Plug-in Version: 0.0.13
Plug-in File Version: 2.0.13.0
Plug-in Path: C:\Program Files\iTunes\Plug-ins\itw_scrobbler.dll
No drives showed up to be tested.