Hi, amedus,
That is the fix that fixed my problem. If the cd is not shown, if it is inserted, try this. Go to Folder OPtions. See if in the general tab, in the folders , both items are checked and see.
Naturally if cd dvd are not working, it is either the third party program disabled it or there is some corruption in the registry.
Please check whether the Hardware detection services in the services are enabled. If this is not, then hardware would not be deducted by the computer. If it is disabled, make it enabled and auto detect. These services are disabled by third party program, particularly dvd programs sometimes. Upper and lower filters might do the trick, if you correctly do. There are many more keys associated with cd rom.
If you meddle with these keys , then it may further corrupt. I think, that registry correction program by Shane would do good to correct , corrupt entries .