With unexplained crashes, a useful tool is Microsoft Visual Studio. You can download and install Microsoft Visual Studio Express (it’s free), hit “Debug/Attach to Process” to attach to the VST Host you are using, then wait for the crash. Visual Studio will 'catch' the crash as it happens, and allow you to see what module caused this crash by checking the ‘call stack’ – which shows the filename of the module involved in the crash.
Often this will identify a specific module which is causing the problem. Other times the information only points to the host DAW, or the SynthEdit plugin, which is less useful.
You might also need to download the ‘platform SDK’ (which supports c++ projects).