[Hoary] No CDs/DVDs mount - ISO9660 is an "unknown type"

[Ben Novack]

I had a working DVD drive when I went to bed last night; I even
watched a movie through libdvdcss and totem-xine without a problem.
This morning, any disc - including the Hoary Preview disc I installed
from - gives me this when I click on it:
"mount: unknown filesystem type 'iso9660'"

What might have gotten broken? I ran hdparm to enable dma on my dvd
player last night to get acceptable movie performance, might that have
been the problem?

--Ben