I am using 3CX Phone System Version 9, with a bunch of users on the 3CX softphone, version 4.0.13527.0. I have a handful of workers in a remote office connecting using the 3CXTunnel. All of these users have the same connection settings, are running XP Pro, have almost identical computer models, and perform the same daily functions. All users can call internally and externally, except for one user. This user can place outbound calls (cell phone numbers, land lines, etc.), and everything functions as expected. However, when this user attempts to call an internal extension, they are not able to hang up and end the call. What I mean by this: The user presses the "end call" button and the phone freezes up and apparently crashes. The user will remain on the line until the other party ends the call, or until he kills the 3cxphone.exe process in task manager. The user can't click any buttons on the 3CX Phone, and the call still shows as connected. Both parties continue are able to still converse until the other party ends the call or my user kills the process in task manager. This user can hang up and end calls to external numbers without incident. So far I've been looking at software related issues. I've gone through programs looking for something incompatible, without much luck. I've uninstalled and reinstalled the software a number of times with the same results each time. Could this be a known issue with the v4 software? Is there any place I could download v3 to test this out? Thanks.