Posting to the Windows Fortran forum is not going to help you much. What you seem to be doing is to call the Matlab engine from your Fortran code, with libeng.dll acting as the go-between; within Matlab, you could be doing anything -- as simple as displaying "Hello" to something very complex, such as calculating next week's weather forecast. If something can go wrong in any part of that complex chain, it may (Murphy thinks it will), and cause the whole thing to crash. Nobody can tell you how to find and fix the error in a few sentences.
