Oops, todays update = dead screensaver

Dear all,

I use a screensaver that I wrote myself in .NET 1.1 whose job is to
kill off unnecessary processes (ITunes' Ipodservice, Realplayer
update, etc) that vendors in their infinite wisdom choose to make next
to impossible to disable permanently. It has worked fine until today's
updates, when the call Process.Kill is now throwing a 'permission
denied' error.

I see nothing explicit in the update release notes to suggest that
anything's definitely been locked down in this area, though I can well
imagine that it might have been. Can anyone help me confirm what's
going on? Was there something in today's updates that would stop a
screensaver having the ability to kill processes?

I'm running XP Professional.

Thanks in advance,

Clive