about crossover I have no clue
but check if you have libcanberra-gtk3-module.so() and libcanberra-gtk-module.so() on your system

And about the title of this bug, it is not appropriate I think
better to change it to something like "Python gtk crash or missing lib"

By the way, which DE are you using ?
Which theme ? oxygen-gtk ?

Found
it is a bug with python-gtk
easy to reproduce
this script (test1.py) fail :
#!/usr/bin/python
import gtk
gtk.gdk.threads_init()
raw_input("If this didn't crash, hit enter.")

$ ./test1.py 
If this didn't crash, hit enter.Attempt to unlock mutex that was not locked
Aborted

this one (test2.py) is ok :
#!/usr/bin/python
import gtk
gtk.gdk.threads_init()
gtk.gdk.threads_enter()
raw_input("If this didn't crash, hit enter.")

$ ./test2.py 
If this didn't crash, hit enter.
$

so, code in mageiawelcome (in fact start_gtk_thread() in webgui.py line 118 need to be changed from :
def start_gtk_thread():
    # Start GTK in its own thread:
    gtk.gdk.threads_init()
    thread.start_new_thread(gtk.main, ())

to 

def start_gtk_thread():
    # Start GTK in its own thread:
    gtk.gdk.threads_init()
    gtk.gdk.threads_enter()
    thread.start_new_thread(gtk.main, ())

cf : 
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=671785

but may be that further change would be need :
https://wiki.gnome.org/Projects/PyGObject/Threading

I assig the bug to mageiawelcome maintainer

Assignee: makowski.mageia => n54
Source RPM: (none) => mageiawelcome-0.8.8-2.mga5.noarch.rpm

Same Problem here.

Regards

CC: (none) => ezequiel_partida

Fixed with mageiawelcome 0.8.9

Status: NEW => RESOLVED
Resolution: (none) => FIXED