[CalendarServer-dev] 10.6 client issue with 10.6 server

I'va coma across two different Mac OS X server 10.6.4 that has issues with certain 10.6 iCal clients: iCal is configureed and finds and loads the calendars, then one or two days later that URL^W address can't be found. deleteing the account from the client and adding it again solves the issue for another day. Has anyone experienced something similar?