indeed it does!
in short:
the cd drive has becom partially unplugged from the laptop.
in long (may be of interest - i guess some of you are pc support pros)
when replacing my HDD i hastily removed every screw from the PC case (pointless exercise- as you probly know - the HDD sinply slots in behind the battery).
one of those screws retains the CD drive - I guess I failed to do it back up tightly enough.
the clue was that the CD panel did not sit perfectly flush with the side of the laptop case.
oddly enough - although the cd drive disappeared from bios + windows, it still span when a CD was placed in the tray. i guess the power pins where just about connected but the data pins not ?

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anway - thanks for your help