Screen locks up and strange pattern a...

Hi all, I've got a problem I haven't encountered after sifting through a few pages of posts on here in different forums.

I upgraded my machine last year as my old mobo completely died to the following system:

* MSI K9 VGM-V mobo

* AMD Athlon 64x2 Dual Core 4800+
2.50GHz

* 2 x 1 GB Ram - Kingston KVR667D2N5/1G
- DDR2. The mobo has an onboard 128 MB
GPU which means my system is left with
1.87GB RAM

* Maxtor 160GB hdd for the system drive
- partitioned in two (the other half
holds all the Bond movies - nice)

* Maxtor 250GB slave hdd for media
storage

* Optorite DVD-RW 1205 dvd drive

* M-Audio Delta 44 soundcard in one of
the PCI slots

* Wireless keyboard and mouse

* Bluetooth USB clip

* Line 6 TonePort UX-1 audio interface
for recording guitar/vocal parts -
connected via USB to the PC for sound
processing and to the inputs on my
soundcard's breakout box for output to
the speakers.

I built the system with a mix of old parts from my old PC (soundcard, DVD drive, and the 160GB Maxtor which was my slave drive in the old PC and is now my system drive), and new bits bought from the local nerd emporium.

Everything was fine for about 6-8 months then it started randomly flipping out. I would be working - either recording music or using the internet, watching a video etc - no one thing seemed to trigger it, and the screen would randomly lock up and look as though it were an old analog TV that had lost its vertical hold (I will post a pic of the screen at the bottom).

The only change I had made to the system up to this point was adding the Line 6 unit but the problem had started occurring about a week before that, and persisted when I ran the system without it, so I've kinda discounted that as the cause of the problem.

I'm not sure if the rest of the PC was functioning in the background but it would also kill the sound if I was listening to/watching something, so I assume everything else went too. The only thing that would cure it is a reboot, until the PC does it again.

I spoke to the shop I got the parts from and they got it in for testing.
First time they couldn't find anything wrong with it,
the second time they told me my mobo was dead,
so it was replaced. I installed the new one and within an hour the same thing happened again, although much less frequently. I took the new one back and it was replaced again, and have installed a third mobo (all the same make+models btw), and once again, the same problem within an hour.

With the most recent mobo change i decided to add another 1GB stick of RAM to speed up my system. The problem I was experiencing before is now also accompanied by random restarts, sometimes the computer will restart - and others it will just trip out n the screen go black as if restarting, but it never quite gets there.

I'm assuming the restarts something to do with the RAM but I'm stumped on the mobo/screen lockup issue, after so many motherboards I'm considering the following:

* the store I bought it from has now
discontinued this particular mobo
- so it's likely quite old, and
suffering from the inherent problems
of being old

* there could be a compatability issue
with some of the other hardware I'm
using in the system

* the problem could be caused by some
other piece of hardware in the system
malfunctioning - bad RAM or HDD
perhaps??

* It could be a bad batch from the
factory

* MSI mobos are really crap and I should
look to another manufacturer

any advice will be gladly welcomed as I'm looking at just scrubbing the whole thing and building another system from the ground up specifically for music use. and while that would be good, it's also expensive and time consuming.

Here is a pic of the screen when the problem occurs. The colours vary with whatever's on the screen at the time, but the pattern always remains the same.

Screen locks up and strange pattern appears