This machine I'm typing on started acting strangely a couple of weeks ago. Performance was jerky and mouse response was spotty. It seemed as if there were some sort of virus stealing a lot of the CPU cycles. I looked in the registry, poked around for any lurking nasties, but found nothing.
The last couple of days the mouse pointer started moving on its own. It would suddenly zip to the top of the screen or go flying about randomly. So today after discounting to my satisfaction possible software issues, I plug in a new mouse and all symptoms have vanished.
Apparently, the mouse hardware went crazy and was unmercifully hammering the CPU with interrupts. Naturally, I had to take the defunct mouse apart and examine its mechanism prior to sending it off to its final reward. This is what engineers do -- we love to examine failed stuff and see what it's made of. This particular rodent had a couple of possible culprits. Its internal circuitry was simple enough - one IC, a couple if infrared LED's and IR sensors, three 3 micro-switches (it was a wheel mouse), and one electrolytic capacitor.
The smart money has to be on the electrolytic cap or the IR sensors be bad. If I had to take a guess, I'd go with the cap being bad first. QC on these things has been notoriously bad over the years, resulting in some really spectacular failures in the field.
I suppose I could have fired up the soldering iron and tried replacing the electrolytic with an equivalent rated tantalum cap, but I just didn't have the patience today for such an adventure. Since the new mouse was only $4 at Big Lots, and I already had the thing in stock, there wasn't much economic motive for trying to resurrect the dead one.
I usually give up on electronics hard. I'm not afraid of warming up the soldering iron and hacking on stuff. Defunct generic Chinese mice that maybe only cost $10 5 years ago just don't seem worth the effort though. If my original MS mouse with the "chicklet" buttons were to go belly up someday, that would be a different story. That one I'd take a crack at repairing because there's some historic value involved. I really hate to send stuff with genuine historic value into the skip.