I seem to be having a similar problem - I'm using an Asus eee pc 701 with Leeenux.
Originally I had to install Leeenux from a bootable SD card as it wouldn't boot from any of the USB ports - so I'm pretty sure the internal card reader was working fine up until now..
Anway, I wanted to add a 32g SD card to use for the main storage... When I pop the card in the reader, nothing happens at all - as per the original poster's problem.
I've tried everything suggested in this thread including going into the BIOS (but it was already switched to 'Finished' anyway)
...to top it all I now seem to have created a further problem - after trying everything I decided to re-install Leeenux but with the OS setting at' Start' (in the hope that switching it back to 'Finished' later on might help)
...but now I can't even boot from the SD card reader! .. This happened right after I tried the solution of editing /etc/fstab ...Now if I try to boot from the SD card reader, I get a very brief error message (it flashes on the screen far too quickly for me to read it) then goes into UNetBootin as usual, but if I choose anything from the menu (Install, Run The Live System etc etc) it just hangs and won't do anything.
I've undone the edit I made to /etc/fstab but the problem persists... If anyone can help with this I'd be very grateful!
.. Ideally I want the computer to be able to recognise the 32g SD card, and to be able to boot from the SD reader in case I ever need to re-install linux
Cheers! (and apologies for the long post!)