After church on Wednesday, Pastor pointed at me. "I need to talk to you," he mouthed. That's usually not a good sign, but I hadn't done anything too stupid lately, so I figured he probably didn't want to talk about me. I was right. His computer was flaking out.

Having, at that point, nothing to go on, I suggested he run SFC.EXE, which scans system files for corruption. It flagged a few files, including user.exe. This isn't always indicative of a problem, but it can be. I had him go ahead and replace the files it flagged. He called me and we walked through the process, then the computer just crashed. Bluescreen, in the kernel. Constant spontaneous crashes were the norm now. And the error messages were never the same, he said.

He asked what causes these things. I told him if I knew precisely, I'd be able to write a book that'd sell a whole lot more copies than my last one. Microsoft doesn't even know why Windows does these things sometimes.

At one point he got an error message that said, in essence, to reinstall Windows. I told him I could walk him through it, but at that point I'd be more comfortable seeing it myself.

So that was what I did yesterday. The computer booted up fine, and I couldn't find anything wrong. So we tried going online. That flaked out--the modem couldn't connect and just gave false busy signals. I brought up HyperTerminal, tried dialing my own phone number with it, and the system crashed. Bluescreen. Kernel. OK, so I reinstalled Windows. It crashed during the installation.

Several things can cause that. I jumped straight to memory. Opening the case, I saw several possibilities. No-name Eastern Rim power supply. A microATX motherboard with the notorious SiS 530 chipset. I told him I'd run a diagnostic on it. Just to be on the safe side, I pulled the memory. It wasn't commodity memory--it was an Apacer module. Apacer isn't the best but it's far from the worst. I cleaned the module's contacts with a dollar bill, then put it back in and turned the system on to see if Windows could pick up where it left off. Note that I didn't replace the case cover. An experienced tech never does that. Why not? I noticed something the minute I turned on the power. The CPU fan wasn't turning. I found the problem. The dead CPU fan, incidentally, was a Vantec. No, not Antec--Vantec. It was a ball-bearing fan, and Vantec is fairly reputable, so this fan just died before its time. It happens sometimes.

So it appeared the crashes were due to overheating.

The local CompUSA didn't have a single Pentium/K6/Mendocino Celeron CPU fan in stock. Bummer, because the marked price on an Antec was $13. So I went to Best Bait-n-Switch, where I found an Antec fan, made in Taiwan (good), for $15. This one had a drive connector, and I'd have preferred one with a motherboard connector, and I'd have preferred a slightly bigger heatsink, but it was all they had, it was bigger than the part it was replacing, and I wanted something right then and there. I bought it, brought it back, swapped it in, and the computer booted up fine, and finished Windows installation without a problem. I even ran Defrag afterward, since that's pretty taxing on the whole system. I let it go for half an hour without a single hiccup. Problem solved, apparently.

It's nice when you can tell someone it wasn't anything they did, that it was a hardware problem. And a CPU fan is a pretty cheap item.