Strange theater map stretch behavior?

[Dutch60]

Normally after starting Lock On FC (1.12a) the theater map looks normal like in the first image.

 

But most of the times when I try to view the theater map from a (declassified) mission created

by ED or some of the great third party missions the map turn’s up all green and then when I press

the button ‘100%’ it gets very strangely stretched like in the picture below the normal map.

 

Is there anyway to prevent this from happening or to do some un-stretching?

 

My interface size is 1280x1024

 

Thanks for any advice!

 

Normal view after fresh start

 

Strangely stretched view after loading third party missions and pressing button ‘100%’