i had gotten a pulled sony u12a 4x dvd burner which is the same hardware as sony DRU500A, the difference is the firmware version. my problem was that my burner recognised my media as 4x but only burnt at 2x. some DVD's would not read at all unless i used neroinfo tool, strangely it read after i started neroinfo.
basically what i gathered from reading many threads on the firmware website was that sony dvd burners only work with certain recordable DVD's (mostly the more expensive one, hmm i wonder why? (royalty fees to sony probably to add the dvd's to their compatability list).
if your sony DVD burner works on all your media and at the right speed you will be lucky. flashing firmware on a sony burner from what i have read is very difficult and may not fix it or make the drive more unstable.
i think this is where i read most of this, not 100% sure. notice how the thread is 6 pages long and full of complaints? hope you like reading: