hi 
am Ahmed "not the first person who asked u and stopped responding
"
i have the same problem ...
i have a windows application developed using C# vs 2005
we also used WCF technology!
and yes ... we are using threading , and ClickOnce deployment
but we changed the ClickOnce deployment to ordenary one!
and we still facing this problem :
Event type clr20r3,P1 civilRegistrationApplication.exe, P2 0.1.0.0, P3 475195ff, P4 system. Servicemodel, P5 3.0.0.0, P6 4545a17d, P7 ef, P8 0, P9 system.typeinitialization, P10 NIL
plz help!!