Losing Main Screen

[Flyco]

May I canvas members for help about a problem that has arisen with my set-up over the past 10-15 days, while I am flying in DCS.

I use three screens; the main for the DCS view, the second for Helios, and the third to display such things as kneeboard, SRS, Teamspeak etc (I have used this set-up, with Windows 10, for some years now. I did replace my PC with an up-dated one, running Windows 11, around six months ago, retaining all the other items of the set-up. This problem has arisen only within the last 2-3 weeks.

In simple terms the main screen is being shut down from left to right, by 20-30 vertical black bars, taking around 5-10 seconds to completely obliterate the main picture. The other 2 monitors are continuing to operate normally. I seem to be able to stop this by selecting a different view using one of the Function keys - after which, pressing F1 returns me to normal.

It does not have the appearance of an equipment failure of any obvious sort - rather it looks like a built-in screen saver or similar. However, I have looked through the Windows 11 manuals, and can find no reference to any such facility. The only change I have made recently is replacing the background screen colour from near-white to a pale grey, to relieve eye-strain. In several hours of use since then, this has only occurred when flying in DCS.

Before I dig any deeper, I would welcome any suggestions or examples of similar behaviour, and, hence, I though it worth asking for inputs from our more knowledgeable members.