A close reading of Device Manager led to the answer. For some reason, all my HDDs
and optical drives were being detected as "ATA Devices", instead of "Scsi" as they
were before. Also, checking on driver info under IDE ATA/ATAPI Controllers listed
each ATA Channel separately, plus the Intel driver...except when you click for
driver details, all that's shown is Microsoft's generic drivers.
I reinstalled Intel INF/Chipset Drivers a few times, but this did nothing.
A reinstallation of the Intel Rapid Storage Technology drivers fixed it. That, apparently,
is where iAstorA and iAstorV are kept. Somehow it got deleted - there's a chance I may have uninstalled
it by mistake, confusing it with Intel Rapid Start, which is something else -
and putting it back set things right.