I am having random restarts in addition to random program crashes (usually IE, Firefox, Mozilla Thunderbird and Dreamweaver MX). The programs tend to crash without warning – they just disappear!

This is getting worse recently since I added 512 RAM. But it was happening when I had 512 RAM. One tech told me I probably had motherboard problems. He suggested that perhaps the memory slots on the motherboard were the problem. Another said I should clean up the hard dive.

So I reformatted my hard drive, reinstalled everything. And the same things are happening.

Should I change motherboard? Or does anybody have another idea?

System:
Micron Millennia® Max XP
Operating System: Windows 2000 Professional Operating System Windows 2000
Processor AMD Athlon XP 1600+ 1.4GHz 1 CPU002096-00 link
Memory 2 512 MB DDR SDRAM
Hard Drive Seagate Snowmass 40GB ATA100 7200RPM 1 HDI001767-00 link
Video Card VisionTek NVIDIA GeForce2 MX 200 32MB 1 VCD001542-01 link
Motherboard Aurora - Gigabyte 7DX Motherboard with Integrated Components (Millennia® Max XP)

Is it the system that crashes or the programs that crash. There are three things that I can think of that might be the cause of the problem.
1. Bad Ram
2. Bad MotherBoard
3. Bad Power Supply

Both the system (sometimes) and the programs (sometimes).

Are you running 2 different speeds of ram(i.e. pc2100 and pc3200)?If so I would return the stick of ram you just purchased and buy the same speed of the original stick. Ram could be incompatible, kingston is a good brand. go to www.4allmemory.com they have a scanner to scan your computer and tells you which ram would be best for your computer.

But it was happening before he upgraded to 1gb of ram. Did u originally upgrade to 512mb from something, or is that the original amount of memory?

When I got the machine in 2001 it had 256 mb. In early 2002 I ugraded to 768. The problem started about 3 months ago (I had not yet made any changes). I updated to 1 mb about 2 weeks ago. It has steadily gotten worse.

How many slots do u have for memory?

Edit:
Nevermind about that question, I looked it up, it wouldn't be the problem I was thinking of.

Do u still have the original stick of memory. Try putting that back in and see if it still does the same thing.

2 slots. I don't have the original any more.

So, is the CPU heatsinc and fan clean of dust . ,maybe try someThermal grease n the cpu .
The powersupply fan clean ,pull the side of the case and leave it off to see if maybe staying cooler helps .
As you can see im thinking HEAT

You can put another fan in your computer if it is a heat issue. Also another reason might be your power supply has died. This happened to me it would shut off after a little bit because there was too much power that the computer needed to run.