MA has dropped the BUD-CAI route from 6th May 2008. Not sure if it is a seasonal thing though. The only flights to CAI are from LHR, MAD and AMM.
There are no oneworld flights to Iceland. BA dropped it some time back. Your itinerary also consists of more than 4 segments in Europe. Overland segments do count as a segment, for tickets issued after July 2007.