Access says "Invalid Product Key" but other Office apps ok..

I am using the Office Suite (Enterprise) under the Home Use Program in
Australia - no issues with installing, activating and using most of the
applications, e.g. Word, Excel, Outlook, etc.

I installed Access from the same package at a later date but when I entered
the SAME product key, it said it was invalid.

I can't raise a support issue with MS directly as it won't let me without a
valid Product ID... which I can't get without a valid Product Key... grrr...

Any ideas? Or any MS reps out there who can help me...?

Thanks,
Mark