Windows 7 Issues after 3CX Assistant Uninstalled

I uninstalled 3CX Assistant 9 from a Windows 7 SP1 Professional machine a couple months ago. Suddenly this past weekend, the "3CXPSTAPI.tsp_unloaded" module started crashing TAPI (error at bottom of post), and whenever it crashed, it brought down the following services:

Cryptographic Services
DNS client
Network Location Awareness
Remote Desktop Service

Even though the services restart automatically, the session has lost its authentication so mapped drives had a red X, Office documents opened in Protected mode, and running standard Windows programs like Event Viewer displayed a UAC prompt with Publisher: Unknown. After a reboot, things worked fine for a few minutes until 3CXPSTAPI crashed again.

Following a tip in this thread, I found that the file 3CXPSTAPI.tsp was still in C:\Windows\System32. I ran this command to unregister it:

C:\Windows\System32>regsvr32 /u 3CXPSTAPI.tsp

That stopped the services crashes and the machine no longer loses authentication.

Manual Uninstall

When I searched for manual uninstall instructions, and found this post. Unfortunately the instructions are incomplete. Here are updated instructions for manual removal (follow after the uninstall):

  • Open Windows Firewall and delete all rules named tcx.assistant.client.
  • Open a command prompt as Administrator and run
    regsvr32 /u C:\Windows\System32\3CXPSTAPI.tsp
  • Check for C:\Windows\System32\3CXPSTAPI.tsp and delete this file.
  • Check for C:\Program Files\3CX Assistant and delete this folder. On a 64-bit machine, look instead for C:\Program File (x86)\3CX Assistant.
  • Check for C:\Program Data\3CX Assistant and delete this folder and subfolders.
  • Check for C:\Users\[username]\AppData\Roaming\3CX Assistant and delete this folder and subfolders.
  • Using Regedit, search for 3CX Assistant and delete all keys and entries[/list]

Full Error

Here is the full error from the crashed 3CXPSTAPI.tsp module:

Log Name:      Application
Source:        Application Error
Event ID:      1000
Level:         Error
Faulting application name: svchost.exe_TapiSrv, version: 6.1.7600.16385, time stamp: 0x4a5bc3c1
Faulting module name: 3CXPSTAPI.tsp_unloaded, version:, time stamp: 0x4d21fed6
Exception code: 0xc0000005
Fault offset: 0x000000018000ae1f
Faulting process id: 0x644
Faulting application start time: 0x01ccf18b2006285a
Faulting application path: C:\Windows\system32\svchost.exe
Faulting module path: 3CXPSTAPI.tsp

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