One common cause for that exact problem, and the fix:
http://support.microsoft.com/kb/q270008/
Although the article pertains to Win 2000, I've seen the problem occur with XP as well; the fix described for Win 2000 works for XP.
Please note that although the article only refers to the "UpperFilters" and "LowerFilters" entries in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet registry subkey, I've had to apply the fix to the similar entries (if found) in the HKEY_LOCAL_MACHINE\SYSTEM\ControlSet00x subkeys as well in order to make it work.
Some people have needed to reboot after deleting the registry entries, others have not.
DMR
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how do you find the UpperFilters" and "LowerFilters"
You need to run the Registry Editor (regedit.exe) to gain access to those items, but there are a couple of "fix" files available for this problem which will save you the hassle (and potential danger) of having to manually edit the Registry. Try this fix (it's for XP, but might work on Vista too):
Download xp_cd_dvd_fix.zip .
* Right-click on the file and choose the "Extract all..." option; follow the Wizard's prompts to extract the enclosed xp_cd_dvd_fix.vbs file.
* Double-click on xp_cd_dvd_fix.vbs to run it. If you receive a confirmation or warning message asking if you really want to run the script, choose YES. When the script finishes running, you will get a message saying that it has done so, and that you should reboot.
* Reboot the computer, and then check Device Manager; your drives should be present again.
DMR
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7,229 posts since Dec 2003
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