c# - System.AccessViolationException in WPF while launching Avaya proactive dialer -

our customers getting below error when launch avaya proactive dialer wpf application.

application: applui.exe framework version: v4.0.30319 description: process terminated due unhandled exception.

exception info: system.accessviolationexception stack:    @ ms.win32.unsafenativemethods.dispatchmessage(system.windows.interop.msg byref)    @ system.windows.threading.dispatcher.pushframeimpl(system.windows.threading.dispatcherframe)    @ system.windows.threading.dispatcher.pushframe(system.windows.threading.dispatcherframe)    @ system.windows.threading.dispatcher.run()    @ system.windows.application.rundispatcher(system.object)    @ system.windows.application.runinternal(system.windows.window)    @ system.windows.application.run(system.windows.window)    @ system.windows.application.run()    @ applui.app.main() 

can suggest might causing error?