Windows 7 Ultimate text size problem

The text does not remain the same size after hibernating and/or re-booting.
I can set the text size as medium, but may end or with large or small.
The text size sometimes will be as requested, and sometimes a different size.
I have tried custom sizes, but that does not work any better.

Sometimes the text will remain stable, but not for many days.
Also (for example) , the large text will be "normal large" and at other times "extra large"
In other words the sizes are not consistent.

I have been told that the monitor can cause this problem, but I have changed monitors and the problem continues.

Any ideas

Problem Continues