HDMI to DisplayPort cable perhaps?
Issue resolved. Changed the following settings on the projector and it fixed it.
Menu > Installation 1 > ActivBoard Installation.
The whiteboard setting needs to be set to 16:10.
Menu > Installation 2 > Advanced > Low Power Mode.
Please turn this Off (by default this will be On.)
Thank you for the update.
I suspect that the low power mode is the one that has resolved it, though actually the issue is 2 fold.
When Low Power mode is on, and then the unit switched off, the video board on the projector is switched off, therefore no EDID information is passed back to the PC when the PC is asking what resolutions can be used, as the PC will not get a response.
With Low Power mode off, the video board holds a small amount of power and the PC can ask the projector for its EDID table and receives a response, and therefore chooses the correct screen resolution.
The 16:10 WhiteBoard installation option forces the image to be 16:10 regardless of the screen resolution being passed into the projector, which will make any screen resolution changes to not be as noticeable.
However when the projector is turned on AFTER the PC is turned on (this is when you see the issue) the graphics card should be asking the projector for its EDID information, but it appears that for whatever reason it is not doing this, and INTEL will be best placed to answer that one.
Hope this explains what might be happening here.
Thanks for the explanation :)