Lets keep the font size discussion over here, as opposed to the thread with start/stop time trimming.
If you use Visual Studio Form design, are you using "AutoScaleMode = AutoScaleMode.Font " instead of "AutoScaleMode = AutoScaleMode.dpi"?
There is a lot of discussion about how things look great in XP and default Win7, but break with font scaling is forced to 120% or 125% by a "custom" theme. Note that "custom theme" includes the one shipped with Win7 that turns off Aero and sets thing to look a lot like XP did...
The bottom line is to NOT lay individual text fields out by using auto-scaling DPI, but let auto-scale font
resize the entire control (not just a field) so that the current font size will fit.
There's some code and discussion over at http://stackoverflow.com/questions/2973165/autoscalemode-problems-with-changed-default-font