Is this file present on your system in this location.
C:\Windows\system32\mshta.exe
If not we may have to replace it manually.
Also from a command prompt trying doing these two commands
sfc /purgecache
sfc /scannow
C:\Windows\system32\mshta.exe
If not we may have to replace it manually.
Also from a command prompt trying doing these two commands
sfc /purgecache
sfc /scannow