I've purchased 4 Plextor PX-716A drives since last December. The oldest has started to have reliability problems burning DVDs. I installed a brand new one in a new audio PC the other night. I think it lasted all of 15 minutes before it refused to recognize a CD. I replaced it today with another brand new one and everything is fine. Anyone else having trouble with these? I bought them specifically to have PlexTools Professional to check CDs after burning.