Business Cards not displaying complete information and/or not working

In the Inbox, when mouse over a User’s name, sometimes the Business Card information displays, and sometimes it does not display. Sometimes only part of the Business Card info is displayed, even if scroll down. We have multiple users at several sights. We are not using Sametime. 99% of our end users are using 8.5.1. A few are using 8.5.2. Many end users are using Windows XP, we have been rolling out Windows 7 for a couple months. There seems to be no common factor causing the problem. Any suggestions?

Subject: Business Cards not displaying complete information and/or not working

I have cleared the local Address Book to ensure it was not pulling the info from the Contacts. Any ideals or suggestions?