Freezing Big Time!

[Sharon Confer]

Hi,

My G4 will sometimes crash on me and I have to do a restart.  The
restart doesn't always work, it loads everything, but when everything is
finished loading, the cursor is frozen in the upper left-hand corner of
the monitor.  I have to restart my computer (Power Button or Reset
Button) over and over until the keyboard and mouse is recognized then
everything works great.  It takes anywhere from 1 to maybe 100 (not an
exaggeration) restarts before the computer is working again.

When I finally get my computer running again, I check the connections to
make sure they're okay, I run Disk First Aid, Norton Utilities, TechTool
Pro, TechTool Lite, I rebuild the desktop, and I've zapped the PRAM a
couple of times...none of this helped.

I took the computer in for servicing (CompUSA) and they said they
couldn't find anything wrong with it, that it started up for them with
no problems.  I then took the keyboard & mouse in and had them check the
computer using my keyboard and mouse -- they said they couldn't find a
problem.

I try to restart my computer using the Mac OS CD, but the computer
ignores my keystrokes (holding down the C).  I also tried to restart and
rebuild the desktop (apple key + option key) and those keyboard commands
were ignored.  This made me think the problem had something to do with
my keyboard and/or mouse so I replaced them with an Macally iKey
keyboard and a Kensington Studio Mouse (optical). I thought the new
keyboard & mouse fixed my problems because I didn't have anymore
crashes.  After a couple months of using the new keyboard & mouse my
computer crashed and I had the same old problem again.  I'm pretty sure
there's a problem with the computer recognizing the keyboard and/or
mouse because the light on my optical mouse doesn't come on after the
extensions and everything else is finished loading.

Does anyone know what could be happening with my computer, and how can I
fix the problem? I hope I'm being clear on describing my problem and
sorry for the long post. Thanks for any help you can give me.

Sharon
G4/450 (Sawtooth)
640 MB Built In Memory
Mac OS 9.2.2