Have had the same problem with the itetrmitnent BSOD on my XPS 400 purchased in Dec 05. DRIVER_IRQL_NOT_LESS_OR_EQUAL iastor.sys. Could not DEFRAG or complete and automatic backup to my SEAGATE Hard Drive, nor could I leave the computer in a wait state for any length of time BSOD. Called numerous techs from DELL, needless to say .no help. Tried several things on my own no help UNITL I found on DELLS website in Journal 06236GFRXB titled Why Does my Computer Freeze When I Run Disk Cleanup or Disk Defrag in Microsoft Windows XP. This procedure tells you to edit your registry and take out the COMPRESSED OLD FILES. I did exactly as it asked and I also noted that there were old MCAFEE files sorry folks I am not a fan and tried my best to uninstall it and all of the other software that Dell included but it doesn't appear it was a total success. So I removed the McAfee and Corel residue .rebooted my machine and I don't know if it is going to last, HOWEVER .I did a complete Backup to my Seagate and a complete DEFRAG without the dreaded BSOD .hope this last for me and hope it may help some of you. BEWARE .take caution when editing your registry be sure to back up the registry file first. I will be watching the blog to see if it works for you. Good Luck