I'll be the first to admit that the appearance of an ominously blue, ominously blank screen followed by an instant shut-down smacks of malware. Well, it smacks of something, and file-eating, process-disrupting intruders are the most likely cause.
They're also the most convenient excuse for explaining away perplexing computer abnormality. As Sara from Southend, U.K., reminds us, however, that might not be exactly the case.
Complete your scans, by all means, but if nothing suspicious turns up, start looking at your hardware, particularly if it's a few years old. Dust, crumbs, and other crud pile up, clogging vents and causing your Old Reliable to overheat. When that happens, checking out is a computer's self-defense mechanism. (It beats combustion, anyhow.)
Sound familiar? Grab a screw driver, some cotton swabs or soft cloth, and a can of compressed air (available at any office supply or computer shop, and possibly drug stores, too) and get to work letting sunlight and freshness into the deep recesses of your neglected machinery--and blowing the bad stuff out.
If that fails to work, it's back to blaming the spyware.