NEC 3550A Multiple Burning CDR Problem

[nwo4life022]

hi i just got two nec 3550a burners along with a benq 1640 i already had and im having problems burning two or 3 at a time with cdrs...for dvds i have no problem as i can burn 3 at a time...i have all the newest firmware and all, but the necs both fail when doing two or 3 at a time...the benq is flawless no matter how many i do....i tried lowering the burn speeds and i will try to change media as i am using philips cdrs...if anyone has any other suggestions please let me know thx