A friend of mine asked me to try figure out what was wrong with their 2 year
old Dell Dimension 4550 computer running Windows XP Home Edition. Over the
last year it has been inclined to have a blank screen (monitor is an
E151FPp) while booting up, and even when the computer boots up successfully,
it invariably will get to a point where the screen freezes, sometimes
preceded by a psychodelic deterioration of the colors. They could never tell
how long it would take until it would freeze up, so they would try to get on
and off as quick as possible.
When I first attempted to boot up the computer, I got a blank screen. With
the monitor powered on, I pushed on some of the other monitor buttons and
got a message that said that the monitor was in some kind of power save
mode, and that I should move the mouse or push any key on the keyboard. That
didn't work. However, I was able to get the monitor to work, by first
disconnecting it completely from the computer, and then allowing the
computer to boot up to what sounded like completion. I then powered down the
computer, hooked the monitor back up, kept the monitor powered down, and
booted the computer up. After the computer had booted up completely, I then
powered up the monitor and there was the Windows XP desktop. In the course
of doing this there were a few occasions where things didn't quite boot up
correctly, and I would get a GGGY (Green-Green-Green-Yellow) diagnostic
light code on the back of the computer. I checked all the IDE connections,
but everything seemed in order. Despite this, I was still able to boot the
computer up. But it seemed that it would eventually freeze up anyway. So I
figured that I would reinstall reinstall XP using the XP Reinstallation CD
in the hopes od eliminating some kind of software issue. I attempted twice
to reinstall XP using the "r" command that would just repair the files that
may have been corrupted. Near the end of both of these attempts, the screen
would deteriorate into a "psychodelic image" followed by a freeze up. I then
decided to choose the option to overwrite Windows XP over the existing
Windows XP installation, and the same thing happened; a "psychodelic
freezeup" at the end of the installation. I suspect that this last attempt
may have deleted some of the configuration files for the existing Windows XP
installation. Also, I suspect that I either created a new problem or broke
something that was failing anyway. Now when I attempt to boot up, I get
nothing on the monitor, and when I look at the diagnostic lights I get a
YYGG configuration implying some kind of memory issue. I attempted to reseat
the existing 256MB memory stick in either of the two banks, and in both
cases the boot process is short-lived and I get nothing at all on the
monitor. I have ordered another memory stick with the hopes that this will
solve the problem, assuming that it is the only problem.

Here are some of my questions:

1)Does this sound like a memory problem that may have been just getting
worse for the last year? Was the GGGY code a precursor to the YYGG code?
Does this imply something other than a memory problem?

2)If new memory solves the problem, how should I go about reinstalling XP?
Is it possible that a virus ruined the first memory stick? Can that happen?
If so, should I totally zero out the hard drive and install XP from scratch
so the virus doesn't ruin the new memory? If not, is there some way of
retrieving the configuration files that I may have deleted on my last
attempt? It would be nice to have the original XP, even though my friend
said it doesn't matter.

3)Should I just format the C drive and just reinstall XP on that. I suspect
that it might be simpler. Would that remove the antivrus program?

4)If the AGP card (I think it's an ATI Radeon 128) was not working properly,
would it cause symptoms like this? I recently removed the AGP card and
attempted to boot up the computer, and I still got the memory error YYGG.

Any thoughts appreciated.