cadence ic6 problem with linux redhat

hello guys .. im not a professional liunx user and have a problem that arises from cadence with linux ..
whenever i open library manager i receive this error : "The Application "wnck-applet" has quit unexpectedly." which stops my windows from appearing in task bar and reaching any window becomes really time consuming specially when i work on a big design with many windows and different processings .. anybody can help ?
thanks