As opposed to the usual software causes of a c0000218, the reasons for my encounters with this BSOD seem to be completely hardware-based.
I have an older Athlon XP computer that will, without fail, crash or fall into an infinite loop whenever I increase the RAM from 2 GB RAM to 3 GB. The computer will even exhibit this behavior even if I add just 512 MB of RAM. However, the computer will not exhibit this behavior if I add a 256 MB DIMM.
Typically, the system should support the upgrade. The motherboard was designed to accept up to 3 GB of RAM and the operating systems that I’ve tested on the machine should have no problem with 3 GB of RAM. RAM, meanwhile, is backwards compatible among generations and types, e.g. a DDR-400 DIMM will typically work in a system limited to DDR-333. However, as I had realized after I had attempted to flash the BIOS to the last available version, the BIOS chip on the motherboard was a locked OEM chip. Not only that, the OEM chip was flashed to a different and older motherboard.
While computers sold by OEMs, like HP, may feature typical retail consumer computer parts, they are not meant to be upgraded by individual users. Instead, such systems are locked at certain specifications via an OEM BIOS chip until they can be serviced by the dealers, the OEM, if were at all. In my case, literally, the computer can support a 2.2 GHz Athlon XP CPU with 512 KB of L2 cache, an AGP 8x graphics card, and 3 GB of RAM, however, due to the OEM BIOS, the PC has been limited to an older CPU design, AGP 4x graphics, and just over 2 GB of RAM.
To resolve this issue, for Christmas, I ordered a non-OEM BIOS chip, a BIOS chip extractor, along with the most powerful CPU and the best RAM modules I could find for the board. This is going to be interesting.