Thanks for your suggestions.
There is one option in the BIOS that I had to change to get XP to recognise the Hard Disk. I changed drive setting from AHCI to IDE mode.
As the writer performs very well, scanned with Benq 1650, I don't think I will bother with the firmware.
The writer operates correctly in Windows 7 so it is not really a problem.
It is just a puzzle that I would have liked to find an answer for.