TOPIC:

You have possibly changed your system default text size from 100% to 125%.

To verify:
Right click on the desktop and select Personalize.
Select Display (in bottom left of screen)
Ensure Smaller - 100% (default) is selected.

This will resolve the problem.

If you absolutely need to use the Medium - 125% setting, then the drop down options can be selected by using the mouse wheel to scroll through the options.

I am trying to change my units of measurement from Meter to Feet using the Settings / General Units dialog, but the drop down nolonger works. In fact none of the drop down list in this dialog work.

Drop down lists in some other dialogs do work.

[TK]