I got a panic call from an old customer that was having a problem that I had not encountered before. Windows XP would not complete the boot process. It would lock up displaying "arcdisp.c" error. A Google search and ten minutes of reading lead me to a memory problem.
I replaced the 512 MB memory stick with a 256 MB stick I had. The computer booted without a problem. I then reinstalled the problem stick, this time in the previously unused bank. It has passed several hours of testing.
I would have eventually found the problem on my own, yet the help from strangers prevented a lot of trial and error. We stand on the shoulders of those that have figured it out the hard way.