For the past 2-3 weeks, my monitor aspect ratio changes every once in a while for no apparent reason. It happens about once per day, sometimes skipping a day, sometimes 2-3 times in a day.

The bottom half of my extra high Windows 98 Start bar disappears, and the title portion of application windows disappear from the top of the screen.

When it first started happening, I used the manual monitor controls to change it back to normal, but this is annoying. For over a week, I have been working with the higher, narrower screen, which returns to normal on its own in 5-15 minutes.

Does anybody know what causes this? The monitor is about 2 years old. Is it about to die? I assume this is a monitor problem, not a video card problem.

yes, usually it is a physical problem with the monitor...either the control circuitry or the power supply....neither of which is a DYI project, but are repairable (but not necessarily cheap to do). But first try it on another machine....and if it still does it then probably time to go shopping...