[ubuntu] Can't boot: 'orphan cleanup on readonly fs'

[tmcw]

This is bad. I can't boot normally - the system ends up with a blinking cursor after going through grub and the first Ubuntu screen. Booting with recovery mode gives the more specific hang message:

Ext3-fs sda2 ophan cleanup on readonly fs

And the Ubuntu Live CD doesn't boot

Also, Puppy Linux will not boot: a unionfs problem, it says.

memtest says everything's fine.

Booting SLAX, it hangs on "Mounting non-root local filesystems"

I can access the ext3 partition from Windows and have copied over my home directory.

I have no idea what to do at this point, I'm never going back to Windows, but Ubuntu seems more toasted than I could ever imagine.