tabs, command buttons, etc are set to system colors. learning this i've set all my forms to system colors so users can change colors by modifying their windows display properties. my users are happy about this because they can be very moody at times about colors.
to learn more about this check your help file and type the word "system colors" then choose "Set color properties to Microsoft Windows system colors".
do you have all of your forms color customed?
hope this helps...