Interesting cube video behavior

[butlwl1 at wfu.edu]

Fellow list-ers,
My cube has been exhibiting some odd video behavior as of late. I'm
currently using my stock ATI Rage 128 Pro card (16MB) to drive an older IBM
17" CRT monitor set at 1024x768,85Hz. Every few minutes, the screen will dim
a bit and then gradually return to normal brightness. Sometimes, the screen
will become ever-so-slightly distorted in the middle for about 3 seconds
before returning to normal. Any CRT aficionados out there know if is this
the sign that the CRT is starting to go bad? Or should I be concerned about
the graphic card (possibly overheating)? The cube is totally stock 450MHz
but was upgraded with the quiet Western Digital 80gig HD. Any help on this
matter would be greatly appreciated, as I'm probably replacing this CRT soon
and would like to donate it in full working order. Thanks all.

-Will Butler
butlwl1 at wfu.edu