Try switching to a different font, preferably a True Type font. True Type fonts have rotation information built into the font. Non-True Type fonts, like Courier, do not have this kind of information. Because of this, rotated text labels will not appear properly on the screen. You can open the Fonts control panel to see which fonts are True Type fonts.
KaleidaGraph is a thoughtfully designed graphing and data analysis application for research scientists, as well as for those in business and engineering fields. It produces publication-quality graphs, and easily converts the most complex data into a functional display.