CHM documents cannot be opened, error message: "Cannot open the file: mk :@MSITStore: File Path\FileName."
Solution:
Method One:
First, download hhupd.exe from the Microsoft website and install hh.exe, then run it. Next, run the command "regsvr32 C:\windows\system\hhopen.ocx" for CHM-related files. If you still cannot open CHM documents properly, check the registry key "HKEY_CLASSES_ROOT\chm.file\shell\open\command". If there is an additional "command" string under this branch besides the default item, delete it. This will allow CHM files to open normally.
Method Two: