Nothing happens when you select View Source option in Internet Explorer.
This happend to me after upgrading from IE8 to IE9 – the View Source option just stopped working. Deleting Temporary Files via IE options menu did not help. The FIX – navigate to “C:\Users\[Your User Name]\AppData\Local\Microsoft\Windows\Temporary Internet Files\Low\Content.IE5\” folder and remove all files/folders including index.dat file. Make sure you can see hidden files/folders when you do that. Also note the [Low] section of the path.