Just the other day, whilst I was working on it normally, and without my having altered any "Settings"/"Display" (etc etc), the monitor of my computer changed to a yellowish hue, and also seemed rather duller or darker. This lasted a few minutes, and then the original tone and lightness returned. I thought at first the electrical power had decreased for a short time, but the problem returned intermittently and now is permanent. As far as I can tell, everything else remains unaffected.   Has anyone else ever experienced this, or can anyone more technologically knowledgeable than I suggest a reason?