Last week Windows Live Calendar got updated, the following bugs got fixed: 

Syncing Calendar - You will no longer see errors resulting from a high CPU usage for the couple of minutes after the calendar sync. You'll also see fewer error messages in general - some issues with checking for new calendar updates and meeting requests were fixed.

Shared Calendars - Some of the rules for settings got fixed – now, when you change the calendar settings for a shared calendar, it is updated for all of the other participants.

Thanks to Steve Boots for the tip.

More than Mail - Calendar Update!