The drive is receiving power and, as I'm using a laptop where there is only one connection to the drive, I believe it is not a connection problem. I will check this as a last resort but taking my laptop apart isn't a particularly simple process.
I have tried checking the registry for the upperfilters and lowerfilters solution but I don't have those in my registry anyway. I have also tried the "cdgone" solution posted on these forums that edits the registry. That didn't work either.
I have tried installing Service Pack 3 and all other available updates but no luck there.
I also tried using system restore with a restore point from a week ago (I was using the drive to play DVDs last week with no problems). This did not fix the problem, although the restore point I chose may have been too recent. I tried an earlier restore point, but after spending 30 minutes "restoring" Windows told me there was not enough disk space to complete the process and so no changes had been made. After making space I found all restore points had been removed for some reason so I wasn't able to go back further.
So... any other suggestions? Any help would be greatly appreciated.