...I do have the film still on my screen...
Hi,
that�s the reason.
The film that is on the screen if you get the PA4X out of the box the first time is NOT for use !!!
It�s only to prevent the screen from dust and scratches... And it may cause electro-static discharges that can cause the "sound-switching".
If you use it for a longe time grease from your finger-tips may reduce the "dis-function" a bit.
You should use a protection-film from a tablet and cut it so that it fit�s.
In germany one dealer sells them fitting for the PA4X ( I gave him the dimensions of the screen and he produced them )