Comment 25 for bug 986654

From post #22 above: "Why? The rule is for "sr" or "removeable" devices. The hard disk is an "sd" device. Why does the change result in issues with the hard disk?"

The reason is that the single udev rule change that "introduced" this issue, actually just created a new, and more probable, way to demonstrate a pre-existing issue.

The motherboard has two IDE controllers, the primary uses interrupt 14 and the secondary uses interrupt 15. It turns out that those two interrupts do not co-habitat well, and perhaps never did. The single line udev rule change that started this whole saga, also created a steady stream of interrupt 15's, even if the CD-ROM drive was not being used. The hard drive was on the primary IDE controller, using interrupt 14. The CD-ROM drive was on the secondary IDE controller using interrupt 15. Before, the single line udev rule change, there was never an interrupt 15 if the CD-ROM drive was not being used.

So now the question becomes why do the two interrupts not work well together, particularly when one considers that they are so very basic to IDE and PATA systems?