When you are unable to open EXE file and they open in notepad or other programs, then that means that the file association for the exe files are messed up, probably by a program or by mistakenly associating with another
However, this issue can be easily removed by following these steps below:
This is a common problem when files are incorrectly associated either by changing default file associations or accidentally opening a file with another program where it set as default such as (notepad, paint, wordpad etc).
To fix the issue, please download and run the registry editor key from here
Right click on the download exefile_cu.reg file and select “Open With”, In “open with” select Registry Editor and when prompted to confirm, select Yes.
Click Start and type regedit
Hit Enter and in the Registry Editor window select File -> Import
Choose the downloaded exefix_cu.reg file and click open to import it.
It will overwrite the incorrect values on your registry with the correct ones.