Ok I just got this same error when I bought a 256 mb ram chip for my e500 apparently they make low density and high density ram also synchronized and non synch you have to use the snych in pairs 2 256 2 128 etc for the laptop to work properly if you make sure the ram chips are both the same or you have only 1 or 2 NON snch it should work fine. Hope that helps.
Here Goes:
A PIII 700mhz Compaq Armada e500 with the integrated video/audio cards 20G HD running WinXP SP2.
Within the last 2 weeks or so, my laptop would be running normal (Programs running) when all of a sudden, a blue screen would pop up (Audio would go into a constant medium tone) with the following message:
***HARDWARE MALFUNCTION
Call your hardware vendor for support
NMI: Parity Check/Memory Parity Error
***The System Has Halted***
I just restarted the computer and it worked fine.
Well, just the other day I went to open a Windows Video file and the HD light stayed on, but there was no activity. The mouse would intermittently freeze, and I was unable to start/close and programs/windows. I just would end up having to disconnect the battery and power supply and restart the computer. No problems. This same type of incident occured Friday, when I unplugged the power supplies and rebooted, the computer went through it's normal bootup series. When it got to the WINDOWS XP screen, it would show loading (the bar was moving) then all of a sudden, a blue screen with some message on it flashed up (too quick to read) and the computer rebooted itself. Then it gets to the Windows did not boot properly and asks to select safe mode etc. I tried all those and still nothing.
I tried removing/changing the RAM, removing the DVD drive, the floppy drive, the network card, the wireless PCMCIA card, everything and rebooted and still the same thing.
I put in my old HD and now it works. Is it possibly my HD gone bad, or is there something possibly corrupt in the Windows XP software that caused this? A virus?
Any help would be appreciated. If this is in the wrong forum, please let me know.
Thanks.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic