I'm having the same problem.. I'm hooked-up with the game cap pro so its all hdmi connected for full HD.
I have 2 monitors on my pc.
The software all works fine except for the green 'Start Capture' button then, it lets me record for '00.00.01' then it does a wierd thing with the screen (verry short time) and stops NO video is even saved!
I have checked the settings not much there...
I gave the program high priority on my pc still the same problem nothing has fixed it till now.
Lucky the 'Start Pre-Roll' button does work and lets me record freely how long as i want and saves the clips to.