Nothing on task bar works or opens, runs WerFault.exe if anything is clicked

Solution 1:

The dump shows an Access Denied error:

Stowed Exception Array @ 0x00000095c833dae0

Stowed Exception #1 @ 0x00000283e6810138
    0x80070005 (FACILITY_WIN32 - Win32 Undecorated Error Codes): E_ACCESSDENIED - General access denied error

    Stack    : 0x283e6815780
        7ff9d4c11734 combase!RoOriginateError+0x54
        7ff9cfd93f20 wincorlib!Platform::Details::ReCreateException+0x90
        7ff9cfdbcfb7 wincorlib!__abi_WinRTraiseAccessDeniedException+0x17
        7ff7f577b306 ShellExperienceHost!__abi_WinRTraiseException+0xca
        7ff7f5746374 ShellExperienceHost!Windows::UI::Xaml::Application::Start+0x94
        7ff7f57462d0 ShellExperienceHost!main+0x40
        7ff7f574a82e ShellExperienceHost!_main+0xa6
        7ff7f574a041 ShellExperienceHost!__mainCRTStartup+0x1ad
        7ff9d3cf8102 kernel32!BaseThreadInitThunk+0x22
        7ff9d4fec264 ntdll!RtlUserThreadStart+0x34

0:000> !PDE.dse 00000095c833dae0
Stowed Exception Array @ 0x00000095c833dae0

Stowed Exception #1 @ 0x00000283e6810138
    0x80070005 (FACILITY_WIN32 - Win32 Undecorated Error Codes): E_ACCESSDENIED - General access denied error

    Stack    : 0x283e6815780
        7ff9d4c11734 combase!RoOriginateError+0x54
        7ff9cfd93f20 wincorlib!Platform::Details::ReCreateException+0x90
        7ff9cfdbcfb7 wincorlib!__abi_WinRTraiseAccessDeniedException+0x17
        7ff7f577b306 ShellExperienceHost!__abi_WinRTraiseException+0xca
        7ff7f5746374 ShellExperienceHost!Windows::UI::Xaml::Application::Start+0x94
        7ff7f57462d0 ShellExperienceHost!main+0x40
        7ff7f574a82e ShellExperienceHost!_main+0xa6
        7ff7f574a041 ShellExperienceHost!__mainCRTStartup+0x1ad
        7ff9d3cf8102 kernel32!BaseThreadInitThunk+0x22
        7ff9d4fec264 ntdll!RtlUserThreadStart+0x34

0:000> !PDE.dse 00000095c833dae0
Stowed Exception Array @ 0x00000095c833dae0

Stowed Exception #1 @ 0x00000283e6810138
    0x80070005 (FACILITY_WIN32 - Win32 Undecorated Error Codes): E_ACCESSDENIED - General access denied error

    Stack    : 0x283e6815780
        7ff9d4c11734 combase!RoOriginateError+0x54
        7ff9cfd93f20 wincorlib!Platform::Details::ReCreateException+0x90
        7ff9cfdbcfb7 wincorlib!__abi_WinRTraiseAccessDeniedException+0x17
        7ff7f577b306 ShellExperienceHost!__abi_WinRTraiseException+0xca
        7ff7f5746374 ShellExperienceHost!Windows::UI::Xaml::Application::Start+0x94
        7ff7f57462d0 ShellExperienceHost!main+0x40
        7ff7f574a82e ShellExperienceHost!_main+0xa6
        7ff7f574a041 ShellExperienceHost!__mainCRTStartup+0x1ad
        7ff9d3cf8102 kernel32!BaseThreadInitThunk+0x22
        7ff9d4fec264 ntdll!RtlUserThreadStart+0x34

Run Process Monitor in background, while trying to open the startmenu or any other operation which causes the crash, and look in the Result column which operation fails with Access Denied error.

Also try to run this update which repairs the ACL which also can cause the errors.

Solution 2:

One of our Windows 10 PCs exhibited this behaviour after the anniversary update was installed. Clicking on the start menu wouldn't work. When I looked in the Event Log it said:

Faulting application name: ShellExperienceHost.exe, version: 10.0.14393.187, time stamp: 0x57cf9d73
Faulting module name: nvumdshimx.dll, version: 21.21.13.6909, time stamp: 0x579f36b5
Exception code: 0xc0000005
Fault offset: 0x0000000000051979
Faulting process id: 0x1594
Faulting application start time: 0x01d2290588da8cb1

The faulting module nvumdshimx.dll turned out to be part of an Nvidia driver installation. Once I removed the Nvidia drivers the start menu worked again.