When connecting to a Citrix XenDesktop 4 virtual desktop you may receive the following error:

"Your computer could not connect to the desktop. This problem may only be temporary. Click OK and then try starting the desktop again. If the problem persists, contact your system administrator."

In addition, the following event will appear in the Application Event log of the virtual desktop:

Log Name: Application
Source: Citrix CGP Server Service
Event ID: 1004
Level: Error
Keywords: Classic
Description:
The service has detected an error (1505) No connection could be made because the target machine actively refused it. at : 161.

This issue is seen with the Citrix Desktop Receiver version 10.

Upgrade the connecting workstation to the Citrix Online Plug-in version 11 or later.