Two Experts and I thought this was solved. It is not. Here are some of the facts:
1. Computer is a Dell M4800 workstation laptop with premium 3200 x 1800 display.
2. I have always had it set at native resolution and magnification set to 200% which is the recommended setting.
3. When opening most any website it will be normal resolution. When I click to most any other linked site the res goes down to an unreadable 25%. Both Chrome and Firefox exhibit this problem.
4. I have already removed ALL extensions and rebooted but the problem still shows up.
5. If, when it is showing in 25% i change the setting to 100% and return to the previous page the previous page still is OK at 100%, but when returning to the previous page I find that it has reverted back to 25%.
6. In the hopes my video driver was out of date I did install the latest version Nvidia. It did not make any difference.
7. Nothing else seems be be giving any problems with this computer.