This is what worked for me.....and how I got to be in this problem.
Out of the blue I guess, didn't really notice, my CD drive vanished, no longer appeared in the "My Computer" screen. The solution I found at that time was to delete the upper and lower registry filters. Yeah, that worked, CD drive back. What I was not aware of was that deleting those filters lead to the itunes registry messages that everybody is refering to, along with the inability to burn a CD in Itunes. Uninstall/reinstall was no help.
Follow the directions in this link: http://support.apple.com/kb/TS2372?viewlocale=en_US
Follow it to the letter until step 11. At step 11 (step #'s refering to the XP instructions) it states to delete the lower filter, which I had done previously so it was not present, go on to step 12.
Step 12 says to right click on UpperFilter, which I had also deleted. The trick here is to ADD IT BACK IN!! Do this by right click on the right side of the Regedit screen, select "New", select "Multi-String Value", name it "UpperFilters". Your Regedit window should now look exactly like the picture in the instructions link. Now continue with step 12, modify your new "UpperFilters" by right clicking on it. Since you just added it, there will be no value data to delete so step 14 can be ignored. Enter value data per step 15 & hit enter. Click ok, reboot and you should be good.
I just did this tonight and after rebooting my CD drive was still visible and working, Itunes did not give me any errors when loading & I was able to burn a CD with Itunes.
Good luck, I hope this helps. It was ******* me off and I suspect others as well.