printer configuration dialog hangs

I have also exactly 10 network printers and I have tried hard to get system-config-printer to freeze. I even have introduced a timeout for the network scan or have changed code so that the results of the network scan are not put together nicely. It always works for me. So I ask you to do the following:

Run in a terminal window

system-config-printer --debug

do all needed actions to get system-config-printer getting stuck, and post the output in the terminal window here.

Run also in a terminal window and post all output here:

lpinfo --include-schemes='dnssd,snmp' -v

lpinfo --include-schemes='dnssd,snmp' --timeout=30 -v

I have the exact same problem.
Here is my output when running the program as Till Kamppeter said.

system-config-printer --debug
Connected as user emil
refresh
Created subscription 7
<monitor.Monitor instance at 0xaa47f8c>: printers and jobs lists provided
update_jobs
Authentication pass: 1
Authentication: password callback set
Authentication pass: 1
Authentication: password callback set
Authentication pass: 1
Authentication: password callback set
get_notifications
update_jobs
Using polkit-1 connection class
+<asyncipp._IPPAuthOperation instance at 0xaa5166c>
New IPPConnection
+<_IPPConnectionThread(Thread-1, initial daemon)>
+<asyncipp.IPPAuthConnection instance at 0xaa515ec>Awaiting further instructions

+<asyncpk1.PK1Connection instance at 0xaa514ec>
+<asyncconn.Connection object at 0xaa515ac>
fetchDevices
Converted ()/{'exclude_schemes': ['dnssd', 'snmp'], 'reply_handler': <bound method _GetDevicesCall._reply_handler of <cupshelpers.cupshelpers._GetDevicesCall object at 0xaa56b6c>>, 'error_handler': <bound method NewPrinterGUI.error_getting_devices of <__main__.NewPrinterGUI instance at 0xaa4746c>>} to (0, [], ['dnssd', 'snmp'])
+_PK1AsyncMethodCall: <asyncpk1._PK1AsyncMethodCall instance at 0xaa56b2c>
Calling PK method DevicesGet
D-Bus call failed: DBusException('The name org.opensuse.CupsPkHelper.Mechanism was not provided by any .service files',)
+<asyncipp._IPPAuthOperation instance at 0xaa56cac>
Next task: (<method 'getDevices' of 'cups.Connection' objects>, (), {'exclude_schemes': ['dnssd', 'snmp']}, <bound method _PK1AsyncMethodCall._ipp_reply_handler of <asyncpk1._PK1AsyncMethodCall instance at 0xaa56b2c>>, <bound method _IPPAuthOperation.error_handler of <asyncipp._IPPAuthOperation instance at 0xaa56cac>>, <bound method _IPPAuthOperation.auth_handler of <asyncipp._IPPAuthOperation instance at 0xaa56cac>>)
-<asyncipp._IPPAuthOperation instance at 0xaa5166c>
Call <method 'getDevices' of 'cups.Connection' objects>
...success
Awaiting further instructions
fetchDevices
Converted ()/{'reply_handler': <bound method _GetDevicesCall._reply_handler of <cupshelpers.cupshelpers._GetDevicesCall object at 0xaa5c04c>>, 'include_schemes': ['dnssd', 'snmp'], 'error_handler': <bound method NewPrinterGUI.error_getting_devices of <__main__.NewPrinterGUI instance at 0xaa4746c>>} to (0, ['dnssd', 'snmp'], [])
+_PK1AsyncMethodCall: <asyncpk1._PK1AsyncMethodCall instance at 0xaa5c0ec>
Calling PK method DevicesGet
D-Bus call failed: DBusException('The name org.opensuse.CupsPkHelper.Mechanism was not provided by any .service files',)
+<asyncipp._IPPAuthOperation instance at 0xaa5c12c>
Next task: (<method 'getDevices' of 'cups.Connection' objects>, (), {'include_schemes': ['dnssd', 'snmp']}, <bound method _PK1AsyncMethodCall._ipp_reply_handler of <asyncpk1._PK1AsyncMethodCall instance at 0xaa5c0ec>>, <bound method _IPPAuthOperation.error_handler of <asyncipp._IPPAuthOperation instance at 0xaa5c12c>>, <bound method _IPPAuthOperation.auth_handler of <asyncipp._IPPAuthOperation instance at 0xaa5c12c>>)
-<asyncipp._IPPAuthOperation instance at 0xaa56cac>
Call <method 'getDevices' of 'cups.Connection' objects>
DESTROY: <asyncpk1._PK1AsyncMethodCall instance a...

I've fixed that traceback in the git repository (fce45be). Not sure if that would have caused the symptom by itself though.

Tim, thanks for the patch. I will upload and updated system-config-printer (with a lot of additional bug fixes) as soon as the Beta-2-Freeze is over.

This bug was fixed in the package system-config-printer - 1.2.0+20100408-0ubuntu1

---------------
system-config-printer (1.2.0+20100408-0ubuntu1) lucid; urgency=low

  [ Till Kamppeter ]
  * New upstream release
     o GIT master snapshot from 08 April 2010
     o For the last update from upstream we accidentally downloaded the
       master branch from GIT and not 1.1.x, so that upstream version from
       Lucid Feature Freeze is 1.1.91 in reality and not 1.1.17 as advertized.
       To fix the bugs of 1.1.91 (an unstable test release) we go now forward
       to 1.2.0 + bug fixes + translation updates.
     o No feature additions expected.
     o This release fixes especially LP: #557199 and LP: #552398
     o Possibly more bugs fixed.
     o Translations updated.
  * debian/patches/53_fix-async-ipp-traceback.patch,
    debian/patches/70_more-async-traceback-fixes.patch,
    debian/patches/73_finally-fixed-race-condition-in-asyncipp.patch: Removed
    patches for upstream fixes.
  * debian/patches/10_menu_entries.patch,
    debian/patches/55_silence_printerdriversinstaller_errors.patch:
    Regenerated to work with new upstream code.
  * debian/system-config-printer-common.install: Added new check-device-ids.py
    file (debug tool, not used by the rest of system-config-printer).
  * debian/system-config-printer-gnome.install: Added man pages.
  * debian/local/testpage-a4.ps, debian/local/testpage-letter.ps: Replaced
    Ubuntu logo by the current one (LP: #542975).
  * debian/patches/84_cache-also-device-id-in-network-printer-search.patch:
    When doing a network printer search on a given IP, cache not only the
    make-and-model string but also the device ID for subsequent connection
    types.
  * debian/patches/86_fill-lpd-queue-list.patch: When probing an IP address
    whether it is an LPD printer and which the valid queue names are, the
    list of valid queue names did not get filled.
  * debian/patches/88_physicaldevice-get-make-model-also-from-makeandmodel.patch:
    Let make and model for a network device also be determined by the
    make-and-model string and not only the device ID (which is often missing
    for detected network printers).
  * debian/patches/90_physicaldevice-clean-socket-uris.patch: When several
    detected network printers are identified as one physical device, remove
    the default port 9100 from socket URIs, to avoid saving entries with
    duplicate URIs.
  * debian/patches/92_do-not-search-driver-for-remote-cups-queues-with-driver.patch:
    If a queue to be set up with "ipp://..." URI points to a remote CUPS queue
    which has already a PPD on the server, we do not need to (and should not)
    search for a PPD/driver to set up locally. Now really recognize such queues
    and suppress driver configuration.
  * debian/patches/57_backend-integration-dnssd-bluetooth.patch: Let Bluetooth
    printers get searched together with network printers, as the search takes
    longer. So USB and parallel printers and also network printer search
    methods appear nearly instantly. In the listing of network printers let
    not only IP addresses but also DNS-SD names appear.

  [ Julien Lavergne ]
  * debian/pat...