While launching the published application in XenApp 6.0 in Windows 2008 R2 SP1, users may face a deadlock and the server become unresponsive. The sessions already connected might get disconnected and prevent servers from accepting new connections.
To fix the above issue please install the Hotfix Rollup Pack 2 for XenApp 6.0 and it can be found in http://support.citrix.com/article/CTX133882.
While installing Hotfix Rollup Pack 1 for XenApp 6.5 and Hotfix Rollup Pack 2 for XenApp 6.0 the installation might fail with the with the error “Installation ended prematurely because of an error”. You may also see some error message related to MS DTC like “MS DTC corrupted”. The cause may be due to the uninstallation of IIS role before installing XenApp 6.0
To fix the above issue go to the command prompt and type “msdtc -resetlog” and enter. Then type “net start msdtc”. Now try to install the Hotfix Rollup Pack!

After uninstalling XenApp 6.x from a Windows server 2008 R2, we can not RDP to the server. The installation of XenApp 6.x modifies the RDP connection in the registry. When uninstalling XenApp 6.x, this original value must be copied back to ‘LoadableProtocol_Object’, but in most of the cases the original settings are not restored.

1. Remotely connect to the registry of the Server
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\Winstations\RDP-Tcp.
There are 2 values as below:
1) CitrixBackupRdpTcpLoadableProtocolObject (REG_SZ)
2) LoadableProtocol_Object (REG_SZ)
3. Copy the value of CitrixBackupRdpTcpLoadableProtocolObject (must be {18b726bb-6fe6-4fb9-9276-ed57ce7c7cb2}) to LoadableProtocol_Object.
4. Restart the Remote Desktop Services service on the affected machine.
5. Delete the CitrixBackupRdpTcpLoadableProtocolObject value.