There appears to be some kind of problem with the way that Windows XP Themes sometimes interacts with some of the controls in a program. Symptoms include black buttons or column headers, missing buttons, HSL to RGB errors, etc.
Most of the time, these problems can be resolved by changing the Windows XP theme to another theme. Right-click on the desktop and choose Properties. On the Themes page, select a different theme and click Apply. Usually, you can then change back to the theme you were using without the problem reappearing.