Address objects cannot be displayed

I have two 300C Fortigates, both running v5.2.13,build762.  As of this morning I cannot access the Address objects via the web interface on either firewall.  I can access other items under the Objects node, like VIPs, or services.  If I try to access the Addresses screen under Policy and Objects I get the spinning progress indicator and it never goes away.  Neither firewall is reporting high resource utilization.  Has anyone else encountered this?  I'll probably just reboot tohe one firewall that isn't mission critical, but rebooting the other one will be tricky due the business demands.