I have a Dell E521 desktop. Recently, my original Dell DVD-ROM has been "flaky" - sometimes wouldn't read. I decided to replace it with a SONY-NEC Optiarc AD-7241S-OB. This is a DVD-RW with lightscribe. When I put in the new drive (leaving the existing original Dell DVD-RW drive-TSST TS-H653A)), the system boots up fine and after a few seconds goes to BSOD. I get the IRQL.... message. When I put the original DVD-ROM back in all is fine. If I put in ONLY the new SONY-NEC drive it boots fine and all is OK, except that the4 system shows it as a generic CD-ROM drive. Through trial and error, it appears that the SONY-NEC will NOT coexist with either of the original Dell DVD drives. The DVD drives are connected to SATA1 and SATA2. I wonder if the problem is that Dell bios does not support lightscribe?
OK, I have been able to fix the problem, but I am not exactly sure why! I removed both the existing, original TSST DVD drives (1 ROM and 1 RW). The DVD-ROM was on SATA1 and the DVD/RW was on SATA2. I removed them and went into the BIOS and turned off those ports. The only port in use was SATA0 for the hard drive. I re-booted and then shut down the PC. I then attached the new, Optiarc DVD/RW as SATA1. On the reboot, I went into the BIOs to turn on the port and verify that it recognized the Optiarc. It did! I then shut down again and connected the TSST DVD/RW as SATA2. On re-boot I again went into the BIOS and turned on this port and verified that the drive was recognized. After saving the settings, I went into windows and everything is working. I still don't know why, except that I did each step individually rather than in one step. Anyway, don't want to "look a gift horse in the mouth"!
Thanks to those who took the time to assist and suggest.