The instruction at "0xXXXXXXXX" referenced memory at "0xXXXXXXXX", The memory could not be "read". Error thrown when unplugging monitor

I am running an a Windows 7 Embedded Standard with i3, 4GB of ram and a solid state drive. It runs a WPF application. However, if I unplug the monitor and plug it back in, while the application is running, I get the following error:

“The instruction at 0x6f7cd318 referenced memory at 0x00000019. The memory could not be read.”

I have tried running RAM memory test which returned no errors. I have then assembled a brand new system with the exact same hardware and still got the same error. I have also downloaded the latest drivers, and installed the Windows 7 ES from a different image. Also used an older version of the application which I believe has worked before.

Any suggestions what could be causing this?