Unable to connect to the CGP tunnel destination
Citrix users are receiving an error on login: Protocol Driver Error

Event ID 118
The Citrix server is reporting a number of Event ID: 118 errors.
Unable to connect to the CGP tunnel destination (127.1.1.1:1494)

Open the Terminal Services Manager and check for disconnected listeners.
The ICA Listener may be down (disconnected).
Resetting the listener resolved the issue.

Citrix ICA Not Listening On Port 1494 (The same may happens to RDP listener)

Known issues with this security update:
After you install this security update on a Windows Server 2003 SP2-based terminal server, Remote Desktop Protocol (RDP) clients or Independent Computing Architecture (ICA) clients may be unable to connect to the terminal server. To resolve this problem, install hotfix 958476

The following instructions correct the issue until the hotfix can be applied:

1. Identify that ICA is not listening on port 1494.
netstat -an | findstr 1494

2. Open the Terminal Services MMC
tscc.msc

3. Disable ICA and then Enable ICA
Run netstat again to verify ICA is listening on port 1494.