glitch

An unexpected disturbance in the flow of electricity to a PC, network, or server, most commonly due to a power surge or a dirty connection. It can sometimes cause a computer to crash.

A glitch is a hardware problem; a bug is a software problem.

Historical perspective: Trading firm Knight Capital narrowly avoided bankruptcy after a computer glitch resulted in millions of faulty trades in August of 2012. The firm, one of the largest traders of U.S. stocks, lost $440 million in a single day, more than the $289 million it earned in revenue last quarter. A group of investors stepped in this week with a $400 million rescue plan that gives the group a 73 percent stake in the firm at a sizable discount. The deal keeps Knight in business, but “comes at a huge cost to existing shareholders.”