Nov 28, 2007
-   Same issue.
I have Presario 2175 running XP SP2.
It started just recently, the CD/DVD drive does not show up on occasion, sometimes it will, then disappears.
I have tried registery cleaners, updated my bios, check my CD-DVD connections, got another CD-DVD drive (from e-bay that was gauarnteed ok), Modifed the registry for lower/upper filters.
When it shows up, I can play CD's for hours, load software fine. When the system goes into a sleep mode it typically will disapper. It is not easy to get it to "re-appear" multiple re-boots, going from hibernate back with something in the drive seems to work.
I have had the system apart, very tedious and checked all connections. When it disppears it will not show up in device manager. I'm somwhat resigned to believe it's a motherboard issue, but why it will work for hours out of the blue is a mystery.
The only time it disappeard while using it was when I was trying to burn a CD RW, then errored out because the device is missing. Still trying to get it back from that ....
The frustation is it can be so many issues, including the OS it makes it hard to know which is the real issue. There are a numbe of scripts that modify the registry, for some reason when I use them "sometimes" it has an effect.
At this point ... I gues I will put up with it .... somday a new laptop is planned....-  
gleadbet