mmc will not run with a version of internet explorer earlier than 5.5

1. Open Command Prompt as Administrator and run:

sfc /scannow

DISM /Online /Cleanup-Image /RestoreHealth

Restart afterward.

2. Check the IE version in the registry

Press Win+R, type regedit, and go to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer

You should see Version and svcVersion values with something like 9.11.xxxxx or 11.x. If they are missing or show something very low, that’s the cause. On 64-bit Windows, also check:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Internet Explorer

3. Re-register the IE components

In an Administrator Command Prompt:

regsvr32 /s mshtml.dll

regsvr32 /s ieframe.dll

regsvr32 /s jscript.dll

regsvr32 /s vbscript.dll

regsvr32 /s shdocvw.dll

4. Turn the IE feature off and on (Windows 10)

Run optionalfeatures, untick Internet Explorer 11, restart, then tick it again and restart.

5. Last resort: in-place repair

Download the Windows ISO, run setup.exe from it, and choose Keep personal files and apps. This replaces the system files without erasing your data.