wrote in message
oups.com...
This computer monitor will show a momentary, thin horizontal glitch
shoot across the screen. This happens a few times per hour. For several
weeks now, and occurring about once every couple of days, the screen
will suddenly go completely black. When that happens, I turn it off for
an hour or so and then it will function okay again. The occurrence of
the blacking-out is getting more frequent. It now happens 2-3 times a
day.

What would be the likely cause? Thanks.

If you mean a thin horizontal line and if it is a cathode ray tube monitor,
then the vertical deflection circuit is failing.