This list will be updated from time to time with more information, if you would like for me to add information feel free to PM me with your request.
1) Voltage/temp problems:
Download MBM5 or a similar motherboard monitor app. Download PRIME95 and Aquamark3. Start the monitor, then run PRIME95 for an hour or so, checking CPU temp. If it does not crash, close PRIME95 and run Aquamark3 7-10 times in a row. Check mb and CPU temp. If you have no temperature or voltage issues, and neither of these cause a similar reboot/bsod crash, then the problem is specific to Planetside. PS seriously stresses CPUs, something few other games do these days. [PRIME95 stresses CPU and memory specifically, Aquamark3 stresses the video card more than the other two] If your Vcore drops too low, your system will restart. Obviously if your temp goes too high it will restart too. If PRIME95 crashes without a temp or voltage problem, it is possible you may have a bad processor. If you notice the system temp going too high clean out the dust surrounding the power supply fan, cpu fan and video card fan. Build up of dust can cause inefficient air flow and thus causing heating issues. Also, when a system freezes with a "tonal" sound, that is more then likely the cpu fan is no longer functioning.
2) Ground issues:
Another possibility is a poor/nonexistant ground. You can get an outlet tester fairly inexpensively at a hardware store or the hardware section of your local store. A poor ground will eventually fry your power supply and other expensive parts of your system. If you have no ground at all, you may have half-line voltage running though your case, something to be avoided with sensitive electronics, and potentially deadly to you depending on what country you are in and what the line voltage is (some countries use 220-240v as line, this would mean you could get a 110-120v shock). Either of these can cause random system restarts under load as natural capacitance builds up and attempts to discharge through the power supply. Proper ground is essential, not just a safety feature.
3) Incorrect memory settings:
You may be allowing your BIOS to configure your memory settings via the programmable chip the manufacturer sets up on the stick (may be listed as SPD or DMI). If the two sticks you have do not use exactly the same settings, the BIOS may be using settings that are incompatible with one of them. Do some research and find out what the highest latency settings are (I don't do enough of this to remember offhand, but I seem to remember 3-4-4-8 --check it, I am probably wrong), and set those manually in BIOS. You can also check for memory errors by running a program like MemTest86 or GoldMemory. Microsoft also has a memory testing program provided at the following link:
http://oca.microsoft.com/en/windiag.asp
4)Cable short:
Pretty rare, but it happens. IDE cables are prone to this. The cable may have a microscopic tear inside which breaks contact as it warms up. Solution: replace cables and see if it still happens. On a similar note Molex connectors can have this as well.
5)MB or PCI short/power:
Crack in the mb or the connection to the PCI bus causes something to lose or gain electrical contact as the board warms up under load. It is also possible that your mb is not properly grounded to the case.
6)Loose cards/connections:
Make sure your RAM, video card, modem, cables, etc are all seated correctly in their slots. As the board heats up things will expand and something may be losing contact which can cause problems.
7) Incorrect System Clock:
If you have an incorrect system clock this could be an indication that you have been infected by a virus or spyware in which you would want to scan for such with the appropriate software.
More than 512MB RAM in Windows 98/ME:
If you are running more than 512MB of RAM on a Windows 98/ME environment this is an issue that can attribute to instability. See Microsoft Knowledge Base Article 311871.
http://support.microsoft.com/default.aspx?scid=kb;en-us;311871
9) IRQ Assignments:
IRQ assignments and the sharing of these IRQ's is generally not an issue with the Win200/XP operating environment. Exception to this will be if your running constant streaming calls from a NIC, Video and Sound device all off the same Interrupt. Online games can be extremely demanding with this type of data-streaming and the results can be a number of things such as system freeze-ups, hesitations and .exe exceptions. Re-assignments within system BIOS resources can be achieved through the BIOS itself or the jumpering of some pins on the motherboard.
10) Update BIOS/Chipset Drivers:
Old and new motherboards will always have issues with their on-board components and BIOS operations, and thus, these manufactured systems have firmware updates to address these very issues. It could be the way the BIOS assigns resources through it's discovery process or there is a flaw in the way BIOS handles video calls, as an example. Chipset updates are available from Intel, Via and SiS. These updates allow the operating system to re-discover the same components but with updated .sys drivers and .dll's. These updates closely matches the operating system with the hardware components. They also closely align themselves with passing Microsoft hardware quality tests.
11) Setting AGP Aperture/ AGP acceleration / and Fast Writes:
You may want to try to set your AGP Aperture size to 128 or 64 as sometimes higher numbers can cause instability in systems and in turn cause your system to crash. AGP acceleration also can attribute to instability if it is set to 8x and you are having stability problems then try setting the acceleration to 4x. AGP Fast Writes can also cause crashing on some video card chipsets so turning this off can also improve stability.