You are right I didn't think so but I am running at 120 dpi (125% font size). The problem is that with my window resolution that is the minimum size at which the text is readable for me
I've had these type of issues with my own programs before. One thing that I always try to do is to make every textbox (including those accompanying checkboxes) as wide as possible (without overlapping them with any other GUI element. Also I usually put a Tooltip for every GUI element, where the tooltip is the same as the text in the editbox. That way, if the editbox is too small, people can still see the text by putting the mouse over the GUI item. That should take care of most of the issues on your Preferences menus.
For the Groups window I guess that it will be harder to fix. The only thing that I can suggest is to make the window size bigger by default, but that might solve nothing if you are using relative positions for your GUI elements.
P.S.- When spellchecking my posts I noticed that the spellchecker tries to spellcheck everything, including the "smiley" codes and the username. I don't know if that is possible but it'd be better if that could be avoided (I almost changed
into "Thumb" in one of my previous posts!