Comment 6 for bug 583036

There are several bugs in this chain of events:
Bug #571707 concerns the stalling (slowing) of plymouth/mountall progress (the 70% thing), this also leads to plymouth/mountall not acknowledging the C for cancel.

Bug #577331 concerns the fact that the filesystem check, when cancelled sucessfully, cannot be ignored

Bug #582035 concerns the error reported by fsck (making plymouth display "serious errors")

The first two of those are already fixed, the last has been fixed upstream, and in Debian, but is not in ubuntu yet.

I think those three report cover all issues adressed here (and in many other duplicates floating around, unfortunately)