I am sure you are aware of my affinity for the Xen hypervisor. In the last year I have switched over to Citrix Xenserver. With other people managing VMs as well having a nice GUI is helpful. One of my complaints is that the GUI (XenCenter) is a windows only app. C’mon, Citrix, please release a cross platform management console. I’ve got to run a windows VM just to use the GUI (granted I don’t have to use the gui, there is a nice API and console utilities). At any rate today I noticed that I could no longer pull up the console for a windows VM nor could I pull up the performance metrics available in XenCenter. A few searches turned up Kenneth Hunts blog and a post that showed me where to fix it. The windows box running XenCenter has a cache folder located in %AppData%\Citrix\XenCenterMain.exe_Url_xxxxxxxxxx. If you remove the cache you should be able to see the console and performance graphs again. If by chance you remove the entire folder you will need to re-add all dom0s back into XenCenter.