Too many buttons in OnGUI?

I have 10 groups that consist of 3 GUISkin's each and a check for each of the 3 GUI buttons (GuiSkin) within the group. Only the first 4 appear to work correctly, rollover, enter, exit, after that bounding boxes are incorrect or rollover appears not to happen. The groups are just cut and paste with different screen coords. Is there a limit to how many buttons can be handled in an OnGUI? If not any thoughts of what's wrong or a differnt way to handle a large number of buttons?

Thanks