software center freezes with grey screen

[rch]

    My System details: Linux 3.2.0-68-generic-pae i686 i686 (Ubuntu 12.04)
    My problem : whether launched from icon or at command line, Ubuntu Software center freezes on grey screen

    1.I did $ software-center
    =========================
        I got
            2014-09-05 16:42:41,090 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
            2014-09-05 16:42:41,096 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True
            2014-09-05 16:42:42,142 - softwarecenter.ui.gtk3.app - INFO - show_available_packages: search_text is '', app is None.
            And a grey screen
        It wedged until I killed via the red button top left corner
        <<The window "Ubuntu Software Center" is not responding>>

    2. I did
    ========
    As per http://askubuntu.com/questions/133456/can-i-uninstall-and-reinstall-ubuntu-software-center
        sudo apt-get remove software-center
        sudo apt-get autoremove software-center
        sudo apt-get update
        sudo apt-get install software-center

    Launched software-center at command line. Again It wedged until I killed via the red button top left corner

    3. I did
    =========
        cd ~/.config; rm -r software-center
        sudo apt-get --purge --reinstall install software-center
        Launched software-center at command line. Again It wedged until I killed via the red button top left corner

   4. I did software-center --debug
   ===========================
    I got
2014-09-05 17:21:57,183 - softwarecenter.ui.gtk3.em - DEBUG - EM's: 17 15 21
2014-09-05 17:21:57,348 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2014-09-05 17:21:57,353 - softwarecenter.performance - DEBUG - opening the pkginfo: 0.00448513031006
2014-09-05 17:21:57,353 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True
2014-09-05 17:21:57,355 - softwarecenter.performance - DEBUG - opening the xapiandb: 0.00170803070068
2014-09-05 17:21:57,358 - softwarecenter.performance - DEBUG - building the icon cache: 0.0024881362915
2014-09-05 17:21:57,370 - softwarecenter.performance - DEBUG - creating the backend: 0.0121800899506
2014-09-05 17:21:57,370 - softwarecenter.performance - DEBUG - get the app-manager: 5.81741333008e-05
2014-09-05 17:21:57,372 - softwarecenter.ui.gtk3.utils - DEBUG - Softwarecenter style provider for ambiance Gtk theme: /usr/share/software-center/ui/gtk3/css/softwarecenter.css
2014-09-05 17:21:57,393 - softwarecenter.performance - DEBUG - ViewManager: 0.0187640190125
2014-09-05 17:21:57,523 - softwarecenter.performance - DEBUG - building panes: 0.129604101181
2014-09-05 17:21:58,053 - softwarecenter.backend.reviews.rnr - DEBUG - refresh with days_delta: 1
2014-09-05 17:21:58,054 - softwarecenter.backend.spawn_helper - DEBUG - run_generic_piston_helper()
2014-09-05 17:21:58,058 - softwarecenter.backend.spawn_helper - DEBUG - running: '['/usr/share/software-center/piston_generic_helper.py', '--datadir', '/usr/share/software-center/', 'RatingsAndReviewsAPI', 'review_stats', '{"days": 1}']' as pid: '10482'
2014-09-05 17:21:58,059 - softwarecenter.backend.reviews - DEBUG - _retrieve_votes_from_server started
2014-09-05 17:21:58,059 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file
2014-09-05 17:21:58,061 - softwarecenter.ui.gtk3.app - DEBUG - query for the update-database exception 'org.freedesktop.DBus.Error.ServiceUnknown: The name com.ubuntu.Softwarecenter was not provided by any .service files' (probably ok)
2014-09-05 17:21:58,061 - softwarecenter.performance - DEBUG - create review loader: 0.537556886673
2014-09-05 17:21:58,062 - softwarecenter.plugin - DEBUG - no dir ''
2014-09-05 17:21:58,062 - softwarecenter.plugin - DEBUG - no dir '/usr/share/software-center/plugins'
2014-09-05 17:21:58,062 - softwarecenter.plugin - DEBUG - no dir '/home/rch/.local/share/software-center/plugins'
2014-09-05 17:21:58,062 - softwarecenter.plugin - DEBUG - plugins are '[]'
2014-09-05 17:21:58,062 - softwarecenter.performance - DEBUG - create plugin manager: 0.000448942184448
2014-09-05 17:21:58,085 - softwarecenter.performance - DEBUG - create SoftwareCenterApp: 0.776718139648
2014-09-05 17:21:58,302 - softwarecenter.ui.gtk3.app - INFO - show_available_packages: search_text is '', app is None.
2014-09-05 17:21:58,303 - softwarecenter.ui.gtk3.panes.softwarepane - DEBUG - show_appview_spinner
2014-09-05 17:21:58,318 - softwarecenter.ui.gtk3.app - DEBUG - on_menu_file_activate
2014-09-05 17:21:58,388 - softwarecenter.backend.spawn_helper - DEBUG - helper_finished: '10482' '0'
2014-09-05 17:21:58,389 - softwarecenter.backend.spawn_helper - DEBUG - got data for cmd: '['/usr/share/software-center/piston_generic_helper.py',
 '--datadir', '/usr/share/software-center/', 'RatingsAndReviewsAPI', 'review_stats', '{"days": 1}']'
 ='[
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x8ec7e4c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a57b4c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a57bcc>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a57bac>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a5724c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a572ac>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a5726c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a5730c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a572cc>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a5734c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a5732c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a5736c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9a571ac>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149b8c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149acc>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149a8c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149a6c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149a4c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149b6c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149b4c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x9149b2c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x91491ec>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x914964c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x914960c>,
 <softwarecenter.backend.piston.rnrclient_pristine.ReviewsStats object at 0x91495ec>]'
2014-09-05 17:21:58,393 - softwarecenter.ui.gtk3.app - DEBUG - on_review_stats_loaded: '5360'

   5. Your kind help much appreciated
   ===========================

[rch (rch-skynet)]

        SOLUTION
            I have (half) solved the Ubuntu Software Center problem with
                >sudo update-software-center

            Now this works:
                >sudo software-center

            But this still blocks:
                > software-center

        DIAGNOSIS
            If I do plain > software-center
            It blocks at
                softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()

        QUESTIONS
            1. What is "aptcache.open()" doing?
            2. Is the current bug 1366109 the same as +bug/1161751?
               ( https://bugs.launchpad.net/ubuntu/+source/software-center/+bug/1161751 )