That's strange, it is fine on my machine. Can you try the following steps to capture a memory dump for me to debug?
1. Use
this version of MP_Pipeline, and download and extract
Procdump package
2. Load your script into vdub/mpc/whatever player, and close it
3. If the slave process is stuck, double-click "dump_immediately.cmd" in the Procdump package, and accept the agreement
4. A dump file (maybe very big) will be generated, please compress and upload it to any sharing site (Mediafire for example) and send it to me