Description of problem:
After system update some applications can't launch. Primarly those which use qt. Standard gnome applications (firefox, gimp etc.) work normally.

How reproducible:
Do the system update after March 25, and check if some of the qt applications start. Tested with these applications: Skype, VirtualBox, Lasfm player, Netbeans. Games: TuxRacer, XMoto. These applications can't start.

Steps to Reproduce:
1. Run sudo yum update.
2. Try launching skype.
  
Actual results:
Application won't start. You can see it in process list, but there is no visible window shown.

Expected results:
Application would launch.

Additional info:
After update it is still possible to launch these applications using sudo command, so the "sudo skype" would launch skype. But under "su" it won't launch.
The bug is also being discussed at http://forums.fedoraforum.org/showthread.php?t=217900