RH4 Ext touchscreen problems

Hi Guys

I have a RH4 and have recently bought a Iiyama touchscreen for it, after posting here and learning that most driverless touchscreens will work.
The screen does work, but then when the desk is powered down and I come back the next day, the external screen registers its touch on the internal screen ie the touch works, but the desk thinks I've touched the equivalent place on the internal screen. This happens every time, and today the 2 screens actually swapped so touching the ext screen registered on the desk screen, and touching the desk screen registered on the ext monitor.
Each time, recalibrating the screens and rebooting the desk sorts the problem, but it seems wrong to have to do that every day?
Started with 2.5.0 and then upgraded to 2.7.0, behaved the same with both. There is a 'loading please wait' message between the High End splash and Starting Console screens during bootup which I don't remember from before, if that makes any difference?

Thanks