I finally found the issue that crashed the GUI of Pd 0.56.2 on Irix 6.5.22! It was the pd.gif icon. Icons in Irix are .xpm files. This should be a configure update.
IOhannes, if the gif icon works on the Mame emulator, it's because it's patched with Nekoware stuff.
Now on to actually testing Pd 0.56...
Wolfgang