After the server's been running a while we get a pop up message window on the
console. Since the server is co-loacated I don't know the exact message, but
the web server doesn't work until the pop up window's been closed.

The event log says this:
Application popup: jrun.exe - Application Error : The exception Guard Page
Exception A page of memory that marks the end of a data structure, such as a
stack or an array, has been accessed.
(0x80000001) occurred in the application at location 0x0521820f.

Is this a problem with our code? Is this a jrun issue? How could I find which
is the case?

Any help is greatly appreciated.