We had image resource “fugue-2.2.2\icons\image-import.png” added to form’s actionbar. It works on 8.5.1 but will crash at least 8.5, 8.0, 7.0.2, 6.5.3 versions on windows xp and also in Vista.
Lesson learnt: Do not use .png files yet on Lotus Notes Client if all your users aren’t using 8.5.1.