Comment 137 for bug 202490

we figured out what problem was, and I want to repeat to *anyone* here listening:

If you have kernel below 2.6.34, you need to:

Unload and blacklist ricoh_mmc module.
To do so:

sudo modprobe -r ricoh_mmc

and then add
blacklist ricoh_mmc to
/etc/modprobe.d/blacklist.conf

This will make it impossible to use MMC cards, update the kernel if you want to use both.

(You can load that module manually to temporally regain ability to read MMC cards)