Even when DH is disabled? Ummm...I haven't had this problem in a long ass time. See if this works:
1. Enable DH
2. Play the game in Windowed mode
3. Drag the game window over to the primary monitor
4. Exit the game
5. Open the game again, see where it boots- if it boots on the primary monitor, skip steps 6 and 7, if it boots on the second monitor do steps 1-4 again but then go to step 6
6. Turn off DH
7. Open the game
Let me know if this works...it's a shot in the dark, but it might work.