Explorer.exe crashes when right-clicking a specific file type

Hi, your suspicion is right: when Explorer only crashes on one file extension during right-click, a shell extension or context-menu handler is one of the first things I would check.

Open Event Viewer > Windows Logs > Application and look for the Explorer crash. The faulting module can sometimes point straight at the vendor DLL. If not, use a tool like Sysinternals Autoruns or NirSoft ShellExView to disable non-Microsoft context menu handlers for that file type, then re-enable them one at a time until the crash returns.

I would also check the default app association for that extension. Sometimes the broken handler belongs to an app that was partially removed or updated badly. This approach should let you isolate the culprit without resetting Windows.