try deleting the akmenu4.nds and __aio folder from your MicroSD, then recopying the new v1.7 akmenu4.nds and __aio folder to your MicroSD
i'm guessing that your problem is caused by not overwriting some of the existing AKAIO files on your MicroSD
PS:
for what it's worth, i installed AKAIO 1.7 right after a format and experienced no problems. currently very happily playing Blue Dragon clean rom with no issues, even though my sav file was created from a patched rom on AKAIO 1.6 RC2.