Please help -- Insp 8600 DVD+RW module driver problem

I hope someone can help with this...it has me stumped. The slim DVD+RW drive module in my Inspiron 8600 won't work any longer. It doesn't show up in my Computer folder. If I load a CD or DVD into it, it takes it in and I can hear it whirring, but nothing else happens. I tried the following:

• Typing d:/ in RUN ... but it says there is no such drive
• Taking out the module and then putting it back in, in case it was a seating problem. No change.
• Ran virus and spyware scans -- nothing.
• I checked Device Manager and there are two drivers for the DVD drive -- one is called HL-DT-ST DVD+RW GCA-4040N and the other is Generic DVD-ROM SCSI CDROM Device (where the heck did that come from??). Both of them have yellow exclamation marks on them. I uninstalled both, hoping the replacement driver(s) would solve the problem after XP replaced them. No such luck -- the "new" drivers still have yellow exclamation marks on them.
• I also tried uninstalling these drivers and then installing a GWA-4040N driver; the message that came up was something about the installer not being able to find something to install to or not being able to find the drive.

As a probably-related side note, I tried connecting an external HD to the 8600 using a USB cord, but this drive also won't show up/isn't recognized.

Can anyone offer any advice or solutions? I feel like I've hit the wall. Not being able to connect to a DVD drive is a killer since it's used for so many things, including loading software.

Thanks everyone.