[windows][ime] OpenLessIme.dll causes intermittent explorer.exe/taskbar AppHang until OpenLess Voice Input TSF is disabled

[AdonisJC]

Summary

On Windows 11, enabling the OpenLess Voice Input TSF IME appears to cause intermittent explorer.exe / taskbar hangs. The taskbar becomes unclickable, the cursor shows a busy spinner, and Explorer appears to restart/recover after a short while.

After disabling only the OpenLess Voice Input TSF registration and OpenLess auto-start, the issue has not reproduced for 12+ hours. No new explorer.exe AppHang events were logged after the mitigation.

This looks related to the Windows TSF IME component OpenLessIme.dll, but the affected host process is Windows Explorer rather than QQ. It may be related to the same general class of TSF-in-host-process issues as #288, but the symptom is AppHang rather than an immediate access violation crash.

Environment

• OS: Windows 11, build observed as 10.0.26200.8655
• OpenLess: 1.3.8
• OpenLess executable: C:\Program Files\OpenLess\openless.exe
• OpenLess IME DLL: C:\Program Files\OpenLess\windows-ime\x64\OpenLessIme.dll
• OpenLessIme.dll file version/product version: 0.1.0.0
• GPU: NVIDIA RTX 3060 Ti, driver 591.86 observed on the machine
• Other IME present: Rime/Weasel (weasel.dll) remained enabled during the successful mitigation window

Symptoms

Repeatedly, after a period of normal use:

1. Clicking the taskbar stops responding.
2. Mouse cursor shows busy/spinning state.
3. Some active windows may also temporarily stop responding.
4. Explorer/taskbar appears to restart or recover automatically.
5. CPU fan may ramp during the hang.

The problem temporarily goes away after reboot, then returns after some time.

Evidence from Windows Error Reporting / Event Log

Observed repeated explorer.exe hangs before mitigation:

• Event type: AppHangB1
• App: explorer.exe
• Explorer version: 10.0.26100.8655
• Hang Signature: 1c0f
• Hang Type: 134217736
• Bucket ID: 3049408ffd65ab5961d605d6a6ace30a

The Explorer WER report's loaded modules included:

C:\Program Files\OpenLess\windows-ime\x64\OpenLessIme.dll
C:\WINDOWS\system32\weasel.dll
C:\Program Files\Microsoft OneDrive\...\FileSyncShell64.dll
NVIDIA user-mode driver DLLs

After disabling OpenLess Voice Input TSF, current Explorer module inspection no longer shows OpenLessIme.dll; weasel.dll is still loaded, and the issue has not reproduced.

Mitigation Tested

The following targeted mitigation was applied:

1. Removed OpenLess from HKCU\Software\Microsoft\Windows\CurrentVersion\Run auto-start.
2. Disabled OpenLess TSF TIP registration:

HKLM\SOFTWARE\Microsoft\CTF\TIP\{6B9F3F4F-5EE7-42D6-9C61-9F80B03A5D7D}\Enable = 0
HKLM\SOFTWARE\Microsoft\CTF\TIP\{6B9F3F4F-5EE7-42D6-9C61-9F80B03A5D7D}\LanguageProfile\0x00000804\{9B5F5E04-23F6-47DA-9A26-D221F6C3F02E}\Enable = 0

3. Restarted Explorer.

Result:

• OpenLessIme.dll no longer loaded inside explorer.exe.
• No new explorer.exe AppHang entries after 12+ hours of observation.
• Rime/Weasel remained enabled, so the isolation points specifically to the OpenLess TSF component.

Additional Notes

System integrity repair was also checked before isolating OpenLess:

• DISM /RestoreHealth completed successfully.
• Component store check reported no corruption.
• sfc /scannow reported no remaining repair actions.

GPU mitigations such as disabling MPO/HAGS were also tried earlier but did not stop the issue. The issue only stopped after disabling the OpenLess Voice Input TSF component.

Expected Behavior

Installing/enabling OpenLess Voice Input should not intermittently hang Windows Explorer or the taskbar.

Actual Behavior

With OpenLess Voice Input TSF enabled, Explorer/taskbar intermittently enters AppHang and then recovers/restarts. Disabling the OpenLess TSF component stops the issue in the observed environment.