Win 8 when dual booted with Win 7 does not see second drive

I have a Win 7 machine with two drives; boot C with Win 7; D is my data drive.

I partitioned the C drive and "successfully" installed Win 8 on that partition. Seems to work.

When I start Win 8, it reports that the data drive (D) is corrupt and cannot read it.
In Win 7, drive D works fine.

My HP machine is about 4 years old.

Any ideas??