* BSOD (blue screen of death)
* White text helpfully explaining that I need to contact my tech support person.
* Among the gibberish, the phrase, "IQRL_EQUAL_OR_LESS_THAN"
The operating system locks up the computer. Rebooting the computer causes the same symptoms to appear, either near the end of the boot or after some minutes of using software. Since Windows takes nearly six minutes to boot on my 2.4GHz computer, it's a long wait.
Researching the Web found that the error message means two IRQs (interrupt requests) remain in their elevated (L) state. Because of how Windows 2000 interacts with hardware, it has no choice but to lock up.
(Recall that plug-in boards and other pieces of hardware are identified to Windows through their IRQ numbers. The problem is that the original design of the IBM PC did not allow for today's explosion of hardware add-ons -- my computer has eight external peripherals -- and there are not enough IRQ numbers to go around and still be backward-compatbile. Microsoft designed a workaround that allows IRQ numbers to be shared on PCI busses. But sometimes the solution screws up. Windows 98 and earlier allowed us to reassign conflicting IRQs; Windows 2000 and XP do not.)
The good news was that Windows would boot into networked Safe Mode, so I was able to transfer working files over to my notebook computer, and keep working there. Then, I had to figure out how to solve the problem:
Solutions suggested on the Web include:
* Replace the memory, in case it became corrupted.
* Update device drivers, in case a new driver contains code to better handle IRQLs.
* Pull out all boards, and then re-install them one by one, in case one of them as gone bad.
* Relocate boards in different slots, in the hopes that Windows will reassign IRQs.
* Microsoft's only solution is to uninstall any recently sofware or hardware. In my case, there was none.
After each action, reboot the computer to see if the problem exists, for me a wait of 5-6 minutes. Sigh.
Late Wednesday night I had narrowed down the problem to the SCSI and FireWire boards. The SCSI board supports my Epson scanner, HP CD-ROM burner, and Iomega Jaz drive. The FireWire board supports two external 160GB hard drives, the external DVD burner, and input from my digital video camea. These aren't functions I want to lose.
I tried plugging the boards in different slots. At first it did not work. I kept moving around the two boards and waiting through the reboot. Thursday morning it worked, and kept on working.
Well, it did, until I remembered I hadn't plugged in the external drives. I did, and the system locked up. Next I plugged them in one by one, and found it problem lay with one of Maxtor's external drives -- the more important one of the two, 'natch.
Maxtor external drives work through FireWire or USB v2, so I tried the USB connection. Locked up again. So now I am in communication with Maxtor to see if there is a fix.
In the meantime, my computer got so screwed up (the sound no longer worked, etc), I decided to reinstall Windows 2000. I am now in the second day of reinstalling software applications.
To see the list of IRQs and which ones are shared, use the Computer Management program incuded with Windows 2000. Once open, click on:
* System tools
* System information
* Hardware resources
In the screen grab, you can see how the SCSI, FireWire, and graphics boards share IRQs devices hardwired onto the motherboard.
In slow motion (one message per day) Maxtor tech support sent canned responses. After asking me to check a few things, it appears the drive fried itself.
Maxtor did mention these items to be aware of:
* Don't unplug the external drive without first using the Unplug or Eject Hardware utility.
* Don't format the drive with FAT or FAT32 when the operating system uses NTFS (Windows 2000 and XP)
In the end, bad news. The hard drive lost all its data. I have backups for most of the data, but there was a gig of MP3s I hadn't backed up yet. These were MP3s I had made from my collection of cassette tapes, dating back to 1974-1991.
Fortunately, I still have the tapes (piled in a box in our storage room), but I'll have to redigitize them all.