OS X Update 10.5.7 destroyed my iCal-Ins…
OS X Update 10.5.7 destroyed my iCal-Installation. For some reason I had made a copy of the iCall.app which saved me of applying the
OS X 10.5.7Combo-Update, which seemed to be the solution for others.
http://support.apple.com/downloads/Mac_OS_X_10_5_7_Combo_Update