Good news! I managed to do a repair installation by starting the laptop with the XP cd already loaded. The sfc /scannow did repair a bunch of corrupt .dll files but did not solve the problem, i.e. the CD drive not burning any CDs. The manufacturer of the drive (Panasonic) cannot even give me the original firmware for this drive so that idea didn't work either.
Unfortunately neither did the repair installation. Sat around scratching my head until I had the idea to see if it's just my profile or all the profiles on the thing that can't burn CDs. Wouldn't you know it...the other profiles burn. (Not perfectly as sometimes it refuses to accept the cd is burnable until I reboot.)
So now it looks like it's just settings...