Complete freeze ups are nearly always caused by hardware. Software simply can't do that much damage in any secure pre-emptively multitasking operating system. The cynical ones among you will point out that Windows isn't all that secure, but the point remains: hardware is the first probability.

So, why do these problems only manifest when using BOINC? A number of reasons. The processor is running hotter than normal. A poorly cooled computer can easily run into problems. The power drain is also higher. An inadequate power supply can cause the operating system to hang. The unusually intensive memory IO can also highlight existing problems with memory, especially mismatched memory - even if a standard memory test fails to identify a problem. Finally, the BOINC throttle may cause problems, by cycling the processor rapidly and causing the fans to pulse.

All of this means that BOINC has proved useful as a burn-in tool. A couple of my team mates have used it to identify problems with servers before putting them into production.

Steps you can take to prevent this, or deal with it if your computer hangs: if you overclock, stop. Overclocked computers often have stability problems that are exacerbated by running BOINC. Lower the BOINC throttle until the computer is stable. Monitor the CPU temperature, and compare it with the acceptable operating limit (this varies between 60 to 100 degrees).