Hi, You can try to '''Associate a file type or protocol with a program''' via the Windows '''Control Panel''' > [http://windows.microsoft.com/en-us/windows7/Change-which-programs-Windows-uses-by-default Default Programs]. Look for '''.url''' > (ignore existing Firefox) '''Change Program''' and '''Browse''' and select Firefox again. Also, if you have security software (antivirus, firewall etc.) installed, you can try deleting all existing instances of Firefox and its related processes/files in all the different configuration modules/areas of the security software like process monitoring, sub/spawned process control, virtualization, HIPS etc., in addition to the security software's main configuration panel. Instead create new fully allowed/trusted rules for Firefox + its related processes in all the different modules/panels - a genuine/original Firefox installer as well as all the installed EXEs (Application) and DLLs (Application extension) are digitally signed by Mozilla Corporation (right-click > Properties > Digital Signatures). Even otherwise, some security software may also ask again when Firefox and/or its sub processes are started, and you may be able to allow/trust at that time. Please see [https://support.mozilla.org/en-US/kb/Firewalls this]. [http://kb.mozillazine.org/Firewalls AV/Firewalls Configuration]

You can check for issues caused by DDE: *http://kb.mozillazine.org/Windows_error_opening_Internet_shortcut_or_local_HTML_file_-_Firefox