Could I have bad memory slots?

Hi everyone,

My post isn't really about overclocking but hoping someone here can give me a bit of guidance as there seems to be some really knowledgeable people here.

I normally leave my computer running 24/7 and have had no problems other then a failed hard drive in the past 6 or 7 years. I went away for a weekend and came back to find my computer screen saying:

"System Halted, hardware failure contact your vendor"

I automatically got that sick feeling in my gut especially after rebooting and then getting the following error before windows fires up:

TRAP 00000002 Exception
TR=0028 cr0=80000011 cr2=00000000 cr3=00039000 gdt limit=03ft etc. etc. etc.

After doing some Googling (on a friends computer) I found that this could be related to memory. I took out one stick at a time (1GB each), rebooting and getting the same error until I had only a single 1GB stick and then it booted up. I then tried the other memory sticks in the same slot to make sure they were not bad and it boots up every time. As soon as I put in one more memory stick I get the error again. So I've narrowed it down to where it is not the actual memory sticks.

The strange thing is when I first boot up the computer the BIOS does a memory test and would read all 4 GB of memory. Why would this happen?

I am thinking it may be bad memory slots on the motherboard but find it very strange that 3 of the slots went bad all at the same time. Which is what brings me here for your guidance. Do you think I need to purchase a new motherboard?

My system specs are:

Windows XP Professional (32bit)

Motherboard: ECS Elitegroup P965T-A

Link for motherboard (although I do not know if I have version 1.0 or 1.0b): http://www.ecs.com.tw/ECSWebSite/ECSSearch.aspx?menuid=0&lanid=0&keyword=p965

Processor:

Intel® Pentium® 4 Processor 640 supporting HT Technology
(2M Cache, 3.20 GHz, 800 MHz FSB)

The computer is rather old and outdated now as I built this one (with the help of a friend who is knowledgeable about computers) about 7 years ago...I believe. Motherboard and processor were bought together.

I've also read that software could cause this problem but the only software I've installed recently was printer software for an HP printer and everything was working fine after that.

Thank you for any ideas as my computer seems slow now and cannot run my 3D applications without the computer lagging. By the way, I do not get any other errors such as blue screens or the computer turning off by itself etc.

Thanks,

Mark

Honestly, its not that uncommon where memory slots go(or start out) bad. On a 7YO rig, its not too surprising. I would disallow software simply because the problem as you describe seems to happen pre-OS. I've been doing this a long time, and I can't even remember all the times shuffling RAM became a necessity because I couldn't affaord new hardware at the time.
As to a cause, I could only guess. Maybe a power surge.