Cant burn at full speed (Pioneer DVR-216DBK DVD)

[qanda]This thread is about the Pioneer 20x DVD+/- SATA Black. Click here to see full specs[/qanda]I have a Pioneer DVD-212 sata burner, and I use 16x dvd+r, but it seems that I cant bun at full speed anymore, 8x tops. I have tried to reinstall windows but it always ends up only burning at 8x. In the past I have seen 22x using alcohol 120%. I used to be able to burn at 16x all the time, using the same computer components. I have my OS on a 80 gig sata drive and my iso’s are on a 300 gig IDE drive. I have a pentium D 2.8 processor with 4 GB ram running either XP 64 bit or vista Enterprise 64 bit. I ran into this issue with a sony drive, ending up buying a new drive, which fixed the issue but after time the problem comes back. Related software I use is Nero 7, dvdfab 6, alcohol 120%, dvdshrink. Thanks, I hope some one can help.

Post a logfile.
Which EXACT media have you used?