My father has a Dell Inspiron 8100 that has a video problem.

This Dell has the ATI Radeon 7500 Mobility card.

At first, the problem was that sometimes on the desktop there were
vertical lines and "boxes" around the mouse. Wasn't bad and only
happened at certain times.

Also, sometimes if he leave hims laptop on standby and NOT turn it off,
it's fine! Until it gets rebooted.

Now, the video sometimes is completely distorted with horizontial,
vertical, wavy lines. Sometimes you can even read the scree. Almost
looks like when you set a resolution that a monitor can't handle.

Again, this is random and sometimes it's fine.

I thought it was a video card problem, but elimindated that fact today.
I reloaded the OS and updated the driver (the one from Dell). The
video issue is also happening at the Dell logo screen on powerup, which
I believe elimindates the idea its a video driver issue. And yes, it
also occurs on an external monitor, thus eliminating that its a LCD
issue or flex cable issue. Right?

So I'm guessing it's a problem with the video card itself. But why
would sometimes it be totatlly fine for hours or days? I even tried
different power outlets to eliminate "noise" in the power lines.