Blank screen on external monitor when running a Vizard script with Oculus DK2

[mstan]

We are experiencing a very strange issue, when we are using an Oculus DK2 to display a virtual environment in Vizard 5. A standard HP Z24i monitor is also connected to the PC.

Normally, as soon as we start our vizard script, the virtual environment is displayed in the Oculus, and in parallel, it is also shown in a window on the HP monitor. Sometimes this works fine.
But sometimes, in about 50% of the cases when we start the script, it works differently: As soon as we start the script, the monitor is automatically „turned off“ (displays just a black screen, only the oculus displays correctly).
We have no idea, what could explain why it sometimes works normally and sometimes not. This effect is absolutely not related to any settings or changes in the script or the system.

For example:
I start the script -> display works. I stop the script. I start the script again -> display gets black. I stop the script. I start the script again -> display gets black. I stop the script. I start the script again -> display works.

We do nothing else in between the steps described above - no changes in the script, settings, hardware etc., we do not even touch the Oculus… It seems just totally random whether the display works or not.

Also, in the cases when the display gets black as soon as we run the script, the script seems to have some other issues: Some functions in the script do not work normally, sometimes key presses are not „recognized“ and sometimes one has to press Escape multiple times to stop the script. We do not have an explanation for this.

More technical info:
The PC works with Windows 7 Enterprise 64bit, its a Intel Core i7-2600 CPU @3.4GHz, 8GB Ram. The Graphic Card is an AMD Radeon HD 6570 (1024 MB DDR3).

We hope that someone has an explanation and a potential solution.