This issue should be resolved with vCenter 5.1 Update 2, which was released in January:
https://www.vmware.com/support/vsphere5/doc/vsphere-vcenter-server-51u2-release-notes.html
Your vCenter build 1064983 corresponds to 5.1 Update 1 (http://kb.vmware.com/kb/1014508), so make sure to update to U2 first.