This is the Microsoft Windows "Mouse Properties" control panel from Windows XP. It is a fairly large dialog, with five separate tabs of settings, but this critique will focus on one particular confusing aspect.
The top section is labeled "Button Configuration". It contains a check box that lets the user switch the meaning of the left and right mouse buttons. Normally, the left button is the primary button - it is used for clicking on items and dragging items. The right button is the secondary button. Generally, it brings up a menu with context-sensitive options and actions.
If the user clicks on this checkbox, the left and right mouse buttons will be swapped. Now, the left button is the secondary button, and the right button is primary. This leads to an interesting series of events:
This dialog is a rather unique situation, since the user is using an input device to change the properties of that same input device. However, there are some things that might improve the situation. First, the designer should recognize that clicking in this dialog with the wrong button is likely to be a fairly common mistake. Therefore, the tooltip in this window could be customized to tell the user what they (probably) did wrong. This tooltip should be carefully worded so that it is not interpreted as insulting the user.
Second, the dialog could more clearly indicate the state of the mouse properties. A label that simply says "Click with the left button" or "Click with the right button" would make things much clearer.
Finally, the wording of the dialog is confusing. The user has no reason to know what "primary" and "secondary" mean in this context. This is reflected in the fact that explanatory text was added below the checkbox. The wording of the checkbox is not as good as it could be, probably because the designer was trying to use wording that would make sense no matter which button was primary. This could be improved by changing it to a radio button, which would have text like this (with each bullet item being a radio button):