( I have all my Win 7 updates applied. )

My Windows Live Mail - Calendar app on my Win 7 PC was working fine.

I had updated my Outlook.com calendar, connected my local Windows Live Mail app calendar, & later found that my local calendar had been sync'ed with the web. 

I could then add an entry in my local app calendar & soon see it sync'd to my Outlook.com web calendar.

I would also receive an email notification of new/changed/deleted calendar entries.

These expected behaviors lasted a few weeks.

Starting today May 19, 2014, my calendar app is unable to sync with the online calendar.

I am still able to receive mail.

When I switch to the calendar, at the bottom, to the left of "Working online", it constantly flashes "Updating calendar..." alternating with "You calendar has ???".

The alternating text flashes very quickly, and the ??? portion is hidden behind "Updating calendar".

Clicking on the icon to the right of the flashing text causes a very brief pop-up window to appear in the middle of the calendar, appearing to say that the task "Update all calendar events" Completed successfully.

The the text continues to alternate/flash, and the events that I added and changed in the locap app have not been updated in my Outlook.Com calendar.

If I switch to the app mail view, the flashing calendar text continues, until I am able to interrupt it by repeatedly clicking Send/Receive.

( Apparently the calendar update error loop interferes with mail update, at least until a mail update is successful.

So I think Windows Live Mail - Calendar on Win 7 has broken.

Note ... other than MSE updates, my last Win 7 update was May 14 and was successful.

So calendar was working with my currently installed updates.

Someone please advise.

Thanks, John