This won't be news to a lot of people, but I suspect some are like me and tend to look for complicated solutions to simple problems.

My desktop suddenly became unstable. For no apparent reason the screen would go black at random intervals and the machine would become unresponsive. Sometimes system level error messages would appear about OS or hard drive failures but they didn't seem to have any context or make any sense.

I am not a software or hardware expert, but years of tinkering have given me some instincts about this kind of thing and somehow these problems did not 'feel' like what the error messages were telling me.

Not having any better ideas, I decided to give things a good clean. I duct-taped a straw to a vaccum cleaner attachment and sucked out all the accumulated dust. The motherboard wasn't actually too bad but the graphics card and some other bits were pretty dirty. I then unplugged and re-seated the cards and memory chips.

Problem solved! The computer has been working fine for the past days so it looks like I cured it. I mention this for the benefit of anyone like me who may dismiss a little dust as not being all that important.