Assuming you're running Windows XP (or 2000), it's got to be a hardware or driver problem to cause a reboot or BSOD. The most damage application code can do is to bring about a visit from Dr Watson, or just make the application vanish (*poof*), or become unresponsive (hang).
I use FXPad without problems.
Some effects can cause SONAR to crash if you have "Autosave every n changes" enabled (note that using "Autosave every n minutes" is not a problem), but
A couple of (old) effects to avoid...
- Digilogue BlueStereo DX (VST is ok)
- FreeverbX (again, Freeverb VST is ok)