Solution for View Source menu opening Desktop

Problem

Out IT team had do downgrade Internet Explorer on one of the system from IE8 to IE6.

Strange things began to happen after that. One frustrating issue was with clicking on the View -> Source menu in Internet Explorer 6. Instead of opening the page source in notepad, it was opening a new explorer view and showing the Desktop!!!

Googling didn't help - there were plenty of people with the same problem but no solution.

Thankfully, I knew it was a registry corruption issue and was able to identify the fix indirectly from some sites.

Actual Fix

1. Open regedit.
2. Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer.
3. Here, there should be a key called "View Source". Simply delete this key (if you feel unsafe, you can backup just this key before deletion).
4. Restart your internet explorer and the problem is solved!

Actual Cause
In HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer, IE 7 and 8 has a key called "View Source". This contents of this key is used to define which Editor will open when you select View Source from the menu. Unfortunately, when IE 7 or IE 8 gets rolled back to IE6, the contents of the "View Source" key is deleted from registry but not the key itself.
So when IE6 starts, it finds the key and incorrectly expects the editor settings there.
Deleting the "View Source" registry key causes IE to use notepad.exe to display the source by default!