It happens with 1.22 firmware. Download TDB A12L firmware 1.15. Restart after flashing. Download 1.22 A12J firmware. Open the exe with MediaCodeSpeedEdit and check "allow same to same flashing". Flash to 1.22 and restart. It should work fine now.
TDB -
http://tdb.rpc1.org/ (PIONEER DVR-A12L (DVR-112L) TDB Flasher w/Kernel)
1.22 A12J -
http://wwwbsc.pioneer.co.jp/device/f..._FW122EUJ2.EXE (extract the file first)
MediaCodeSpeedEdit -
http://ala42.cdfreaks.com/MCSE/ 