Dear Wouter, when things get bizarre on Windows, I tend to use Sysinternals/Microsoft ProcMon. It is free and can be downloaded here:
https://technet.microsoft.com/en-us/sysinternals/processmonitor.aspx ProcMon shows you all Windows system calls with parameters and error results. You should see the CreatProcess call and possibly can see why it fails. Since Cygwin in the end creates a windows process with windows system calls, it should also help for Cygwin. In case your process does start and fails during initialization, you can also see the Windows system calls it does. If there are DLLs missing, you can also see that. Best regards, Michael Intel Deutschland GmbH Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany Tel: +49 89 99 8853-0, www.intel.de Managing Directors: Christin Eisenschmid, Christian Lamprechter Chairperson of the Supervisory Board: Nicole Lau Registered Office: Munich Commercial Register: Amtsgericht Muenchen HRB 186928