When there is no printer set up and the CUPS frontend is selected, xfprint4 hangs if I click on the (empty) combo box with the available printers. If I set up a printer, everything will work fine.
fixed in CVS, don't know what caused that, i got nothing in gdb and all X system suspend. i fixed it by deactivating the widget if there isn't any printer in list
if you want to use the corrected version you just have to recompile the cups printing-system module and to install it in the right place (should be usr/lib/xfce4/xfprint-plugins on most systems)
I will wait for the next beta, since I have set up a printer by now. Thanks for fixing it!