Last year we migrated all our users to 2010 from 2003. Migration went well and everything seems to be working well. The problem is when a user that was migrated from 2003 wants to share their calendar with a new user that was created in 2010. In Outlook2010 they can click the link in the email and it adds the shared calendar to their calendar list. However in OWA when they click the "Add this calendar" link they get this error: "This folder couldn't be opened. You might not have permission to open it, or it might not exist anymore." But they can manually add the calendar by going to the Calendar page and right-clicking and adding it by hand. This only happens between an ex-2003 user and either another ex-2003 user or a new 2010 user. The link works when a new 2010 user shares their calendar with another user(ex-2003 or 2010).
I've been trying to find a solution and so far I seem to be the only person with this type of problem, that or my google-fu isn't up to speed. :)
thanks in advance
Matt