I can reproduce this on my Debian Sarge installation. I happens only while using a Web Calendar. I can either provide the calendar or the url to use in testing. From a little googling, I think there may be an upstream patch but not sure if that is for this issue or another. All that is required is setting up a webcal and having it checked "ON" to display appointments. It basically consumes %100 CPU every couple of minutes. Email me if you need more details.
Robert
