You (or your friend) might want to try starting fresh...
Copy all your files to the PC, then format with the Panasonic SD Formatter
Get a new copy of AKAIO 1.8.1 and extract the AKMENU4.NDS and __AIO folder to your MicroSD.
Copy any games, homebrew and skins back to your MicroSD card.
AKAIO 1.8.1 has worked flawlessly for me.
But if you want to downgrade, just delete the __AIO folder and AKMENU4.NDS and copy whatever version you want.