[CUPS] GUI applications stuck on print command

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https://bbs.archlinux.org – I have a running CUPS server on this machine (a bridged VBox VM, if somebody cares), from which I'm writing. I also have an amd64 arch box in the other room, which has an USB printer plugged in (with cups-usblp from aur), and everything works fine, if I try to print locally from the arch box it works, and also I can print through IPP from windows boxes.But I can't print anymore from this arch box; cups is up and running, and with the right drivers (I managed to print two weeks ago), and is configure to print through the other machine CUPS server (all permissions are correctly set). E (HowTos)