I am unable to burn any cdrs due to buffer underrun but am able to burn cdrws okay.I have tried turning off all programs in the back ground,ran a defrag and a scandisc still to no avail.I have also tried reinstalling my drivers and using different types of cdrs but still to no avail.I cant understand why i can burn one but not the other,surely both would fail if there was buffer underrun.I dnt know if this helps but once i installed my pscsi card the cd writer has taken over my D drive and shunted my cd rom/dvd rom way out to location L.This card says it will support up to 7 external scsi devices simultaneously.I am using only one but have all these differnt drives listed.My computer is an e-machine with 900 mhz processor windows millenium edition and has 810 celeron with an 30Gb hard drive.