I recently acquired a new client running XenServer 5.5 on a Dell PowerEdge T620 Server. In the XenServer he is running two VMs - 1 x domain controller and 1 x XenApp server where all users login to access their desktop. Users open a web browser from the local workstation, access the website, login and then are presented with their desktop. There is plenty of memory and hard disk space allocated to both VMs and the physical host is in good shape. Several times a week a user will login as described above and when the try access their desktop the receive "Access is denied" error. I am not very proficient in Citrix applications, so I plan to (as part of a larger project) migrate the client away from Citrix and onto Microsoft Hyper-v hypervisor. My challenge is that the project to migrate the servers won't happen until 4-6 months now. So, I really need to determine the best way to troubleshoot the Access is Denied error.