Possibly not. When you install Firefox on the D drive then you normally only install Firefox in a different program folder. Firefox will still create the profile folder in the default location (main profile in AppData\Roaming and caches in AppData\Local) and these would be on the C drive unless you used the Profile Manager to create a profile on the D drive. See also: *http://kb.mozillazine.org/Profile_folder_-_Firefox *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox *https://support.mozilla.org/en-US/kb/Recovering+important+data+from+an+old+profile