Many of us who bought H22L's, at least at Best Buy during their sales, have had some issues with the drive's burns not coming out as well at the H22N burns that have been posted. Also, there's been a 1.01 firmware released for the H22N that has not appeared for the H22L.
It's possible some of the non-Best Buy H22Ls are different/better. (like how Plextor rushed the first batch of 716 drives to BB to make a contract date.. we all know how well that worked out!)
I think they're mostly the same drive, but the firmware is probably slightly different in both leading to slightly different results. Odds are for your problem, they're the same drive.