Matlab Psychophysics Toolbox error when opening screen using multiple monitors

For an experimental task I'm developing I need to be able to open a PTB window on one monitor with GUI indicating task progress etc. on at least one other monitor.

This all works fine in my experimental set up.

However, I also like to do some rewriting at home where I have two monitors but because of my homebuilt pc and the spare monitor I had, one monitor is plugged into my video card vga whereas the second is plugged into the motherboard vga. In terms of windows and all other programs this is working fine.

When I try to run the above task, the step which open a taskwindow in PTB causes matlab to crash (the internal error pop up as described here https://uk.mathworks.com/matlabcentral/answers/276695-showing-matlab-has-encountered-an-internal-problem-and-needs-to-shutdown-and-shuts-down).

Running a very basic PTB demo with only one of the screens connected (either one) works, so I imagine it's something to do with running the extra screen via the motherboard? The minimal demo is this one http://peterscarfe.com/totallyminimaldemo.html

Some basic specs:
Matlab version: 2017b
OS: Windows 10