Using exefix.reg

1.  Boot to option R with a Windows XP restoration disk.
2.  When the CD-R's application is done, select option 1.
3.  Navigate to C:\Windows\Temp
4.  Type: 
       edit exefix.reg  (opens text editor)
5   Type between the lines the following exactly:

----------------------------------------------------
Windows Registry Editor Version 5.00

[-HKEY_CLASSES_ROOT\.exe]
[-HKEY_CURRENT_USER\Software\Classes\.exe]
[-HKEY_CURRENT_USER\Software\Classes\secfile]

[HKEY_CLASSES_ROOT\exefile\shell\open\command]
@="\"%1\" %*"

[HKEY_CLASSES_ROOT\.exe]
@="exefile"
"Content Type"="application/x-msdownload"
----------------------------------------------------

6   File | Save (as exefix.reg)
7.  Exit from the editor.
8.  Type:
       exefix.reg
9.  Reboot the computer to Safe Mode (Administrator)
10. Check the Windows registry to see if the changes took.
11. Install Malwarebytes' Anti-Malware and run a quick scan.
12. Reboot to Windows Normal Mode.
13. Update Malwarebytes' Anti-Malware and run a full scan.

Optional Notes:
1.  Use a Linux disk in live CD mode to rename regedit.exe
    to regedit.com; reboot to Safe Mode Command Prompt;
    try running regedit.com
2.  Safe Mode (Administrator) choose the NO option to try
    a Windows restore point back to a safe date.