Download launches blank window
From MozillaZine Knowledge Base
What and Why
When downloading a file you may find that Firefox launches an unwanted blank window. This occurs because the webmaster has specified that the download start in a new blank window even though this was probably not their intention. This is a known issue, Bug 241972.
The Solution
You can fix the problem by downloading the Disable Targets for Downloads extension.
Note for Webmasters
You can fix the problem on your website by removing target=_blank or window.open from your download links.
