instead of running with elevated priveleges, why not impersonate as the farm administator, surely that user has access to write to the cache
although why is it erring on the cache settings anyways
this looks like a problem with the farm configuration
what does the timer job do, what is the schedule frequency, and how are you delting it?
What server is giving you the error? WFE, AppServer, Indexer?
Is it possible the timer job wasn't deployed successfully on all these servers?