Okay, new binary and source fixes the problem with the program crashing when changing the number of threads -

https://drive.google.com/file/d/0B-5Ax5kejTpMNDVGeDdDU2FVMk0/view?usp=sharing

Should be a bit easier to experiment with now.

Note, it can only use powers of 2 for threads . . . and it rounds up. Choose 3, you'll get 4. Choose 5,6 or 7, you'll get 8.