I just burned a bunch of dvd-rs and the last two took 10 minutes @8x

I burned a bunch of dvd-r’s and they all took the usual 8 minutes. The last two took 10 minutes. before i burned the last two i hooked up my external hd and watched some videos. then i shut it off and safely removed it and burned the last 2 dvd’s. during the second half of the burn it was burning @6x exactly instead of gradually increasing towards 8x like usual. i checked that it’s dma mode and ran a burst rate test like ten times and it’s the normal 42 mb a second. i have a liteon 20a4p burner. this happened on one burn a few days ago, but i took it as an aberration. now what exactly do i do? any problems i’ve ever had before were software conflict causing the burst rate to suffer. the burst rate is normal though. i’m running hdtune to check the hard drive for errors. after that i’ll defrag the hard drive. i have a feeling it’s not going to work. defrag has never solved any computer problems for me ever.

This could be a result of the drive heating up after you “burned a bunch of dvd-r’s” and then deciding during power calibration that it’s not safe to burn your DVD at anything faster than 6x. Drives don’t perform as well when they get too hot.

After the drive has been allowed to cool down, is it still burning only at 6x?