Hi Guys, Thanks for your help. I looks like I might well have a problem wich has been recified in later kernel releases. I'm upgrading my kernel to 2.4.19ac3 today, and will let you know the results. It definitely looks like it is a problem with APIC. I wish I knew how to change the IRQ PCI devices used. I've got all these free IRQs, and my three adaptec SCSI Controllers all want to use the same one. Anyhow, will follow up tommorrow.