another qsi sbw 241 problem

i have had a qsi 242 in my laptop which had the same noise and reading problems as have been described in the other thread in this page.it recently stopped reading altogother(only about 14 months old) so i went ahead and bought a used replacement qsi 241 from ebay.when i tried it it didnt work,wouldn`t read a thing.i then noticed that if it had media in the tray when it was shut down, it would be able to read the disc when it booted up and could read it until the disc was ejected (would not read it if re-inserted).
it would seem to only recognise media when booting up but having done that would then be able to read/write with it until ejected.
i tried another cdrw/dvd combo from a compaq and it worked fine.
does anyone have any ideas,i`ve tried uninstalling the driver to let windows redetect it.i`ve read about firmware in this forum but have not tried changing that.my laptop is a (no name)made in usa i think
thank you for any help
iain