After having the same problem I figured out it happened after I installed
then uninstalled Google Chrome. After researching the problem online I found
the following:
"If you received this error after uninstalling Chrome (or Firefox) browser
you may also need to change the HTM/HTML association in the registry.
1.Start, click Run, type REGEDIT in the Open or Search box, and then click OK.
2.Go to HKEY_CURRENT_USER\Software\Classes\.html
3.Right click the value for the .html key and select Modify...
4.Change the value from "ChromeHTML" to "htmlfile" (or from FireFoxHTML to
htmlfile)
Repeat these steps for htm and .shtml keys if they exist."
I followed these instructions but the problem remained so I went back into
REGEDIT and opened additional items under Classes and found several more that
referenced "ChromeHTML". In each case I deleted the word "Chrome" and added
the word "file" after "HTML".
It worked!