Hi all,
I have (actually my wifes has) a Dell Inspiron 2500 laptop. 800mhz proc., 512 mem, 20 gig HD. About 2 months ago, it kinda just stopped working. All 3 lights would come on HD, power, and battery, but it would not go past this. I went on the net, and one forum suggested re-seating the memory sticks. I did that, ad viola, it started working again. Then again in about 3 days it stopped working again. This time re-seating memory did not do the trick. On occasion it would go to a point of a very garbled screen, and I could tell it was booting. So I plugged a monitor into the back, and could see Windows XP was up and running. Hmm, so I let it run for my wife like this, but after 2 or 3 days it stopped working again. Now here is the strange part, I had been pretty busy, but today I was down in my workshop, and decided to plug it back in and see what would happen. OMG it booted up normally. I took it upstairs to show my wife, and rebooted it, and again nothing but the 3 lights, no booting. I don't get a beep code with the memory out, I will try to find out what that means, but does anyone have an idea of what this could be, and why it came on normally after sitting 2 months?

Most likely you're being affected by a common prob. to all metal parts, oxidation, commonly called rust. Contacts on the ram slots probably need cleaning.
Moisture is always in the air to varying degrees and if it isn't being caused to evaporate frequently (due to being allowed to simply sit and do nothing for long periods) oxidation sets in.