I've seen this situation before and, in my case, it was because Xen API service wasn't working anymore because of lack of disk space (logs filled the disk). I followed this post to fix the problem: http://www.techmediaconsulting.com/index.php/virtualization/citrix-xenserver-run-out-of-disk-space

If it's a production environment and you have Citrix support is better to have them involved though. In my case it was a lab environment.

Daniel

Hi Warren,

Is this resolved?

As Daniel recommended, since this is production, you should get Citrix Support involved.

Regards,
Somesh

The logs were the problem.

Warren