I'm having trouble incorporating multithreading support into my OCaml-Win32
library.  Basically, any program that uses OCaml threading and also invokes
a Win32 message loop will crash after a few seconds with an illegal attempt
to access memory at "0x00000001".  This behavior is demonstrated by the
enclosed sample program, which is very simple and does not require my
OCaml-Win32 library.

I tried following the suggestion from the mailing list of adding "if not
(!Sys.interactive && signal=(-11))" to the preempt function, but it doesn't
seem to help.

I don't really know how to investigate this problem further.  I've
determined that the problem goes away if I disable the tick thread, so
presumably it has something to do with the interaction of the tick thread
and the Windows message loop.  I've also noticed that if I call
enter_blocking_section / leave_blocking_section in my C code, the behavior
changes: the program exits abruptly with no error message.  By inserting
printf's, I've concluded that the GPF and/or abrupt exit do not occur during
execution of any of my C code.  Beyond that, I don't know what to try.

Does anybody have any idea why OCaml's threads might be incompatible with a
Windows message loop, or how I can work on debugging this?