In a number2 atom, when a label ending with '%' (or '%_', as well) is used, right-clicking on the number2 box and selecting "Properties" will cause PD to crash.
I filed a bug report:
http://sourceforge.net/tracker/index.php?func=detail&aid=2030557&gro...
This is happening on Pd version 0.40.3-extended-20080724, and also on 0.40.3-extended-20080603, though it may go back much further. I don't have any older versions handy to test.
I'm running Intel OS X 10.4.11.
Phil Stone pkstonemusic.com