Thanks guys for the suggestions. I added libs and played around with system settings, changing themes and settings which could make a difference. No success. On a second machine phd2 runs fine, but I couln't find what the difference is. Now I fetched the source code and compiled it. Again, no success. Finally, I was able to pin down the problem to some unicode characters in the html code of the About dialog. When I comment out the lines "<td>G\u00FCnter Scholz</td>" and "<td>Iv\u00E1n Zabala</td>", phd2 runs fine. Any ideas?