This is the output when I try to start steam. It closes with the Message "Keine Verbindung zum Steam-Netzwerk möglich..." (No connection to Steam-Network...)

Removing appcache didn't help so far.

running Steam on ubuntu 13.04 64-bit

STEAM_RUNTIME is enabled automatically

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

unlinked 0 orphaned pipes

Gtk-Message: Failed to load module "overlay-scrollbar"

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

[1004/102851:WARNING:proxy_service.cc(646)] PAC support disabled because there is no > system implementation

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Generating new string page texture 2: 48x256, total string texture memory is 49,15 KB

Generating new string page texture 3: 256x256, total string texture memory is 311,30 KB

(steam:12440): GLib-GIO-WARNING **: g_simple_async_result_complete() called from wrong context!

(steam:12440): GLib-GIO-WARNING **: g_simple_async_result_complete() called from wrong context!

(steam:12440): GLib-GIO-WARNING **: g_simple_async_result_complete() called from wrong context!

(steam:12440): GLib-GIO-WARNING **: g_simple_async_result_complete() called from wrong context!

(steam:12440): GLib-GIO-WARNING **: g_simple_async_result_complete() called from wrong context!

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

Installing breakpad exception handler for appid(steam)/version(1370553818_client)

`menu_proxy_module_load': /home/ex00r/.local/share/Steam/ubuntu12_32/steam: undefined symbol: menu_proxy_module_load

(steam:12440): Gtk-WARNING **: Failed to load type module: (null)

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

(steam:12440): LIBDBUSMENU-GLIB-WARNING **: Trying to remove a child that doesn't believe we're it's parent.

roaming config store loaded successfully - 6339 bytes.

migrating temporary roaming config store

Adding license for package 0

Adding license for package 11

Adding license for package 79

Adding license for package 517

Adding license for package 1292

Adding license for package 2243

Adding license for package 2753

Adding license for package 3024

Adding license for package 4314

Adding license for package 4819

Adding license for package 8198

Adding license for package 8892

Adding license for package 11107

Adding license for package 11108

Adding license for package 11262

Adding license for package 13533

Adding license for package 14481

Adding license for package 17982

Adding license for package 32744

Adding license for package 32745

Adding license for package 32747

Generating new string page texture 4: 128x256, total string texture memory is 442,37 KB

Generating new string page texture 5: 384x256, total string texture memory is 835,58 KB

Generating new string page texture 6: 1024x256, total string texture memory is 1,88 MB

Generating new string page texture 7: 512x256, total string texture memory is 2,41 MB

Generating new string page texture 8: 24x256, total string texture memory is 2,43 MB

unlinked 2 orphaned pipes

CAsyncIOManager: 0 threads terminating.  0 reads, 0 writes, 0 deferrals.

CAsyncIOManager: 804 single object sleeps, 0 multi object sleeps

CAsyncIOManager: 0 single object alertable sleeps, 1 multi object alertable sleeps

[2013-10-04 10:28:50] Startup - updater built Jun  6 2013 13:48:29

[2013-10-04 10:28:50] Installation wird überprüft...

[2013-10-04 10:28:50] Verification complete

Shutting down. . .

[2013-10-04 10:29:08] Shutdown