Windows 7: Newly created file extension not displayed in Association List

After Googling how to create a new file extension in Windows 7, and doing so, it does not show up in the list of file extension association definitions. So I can't define it.

The issue I am trying to fix:

During the viewing of a website where we file insurance claims, the result of clicking a link to view a claim file attempts to open an ".aspx" file. Since Windows 7x64 Home lacks this extension listing, it defaults to opening Windows Media Center, as it has an ".asx" association. We want Firefox browser to handle .aspx files.



I successfully created the listing for the .aspx extension in the Control Panel's Indexing sub-settings. But even after a reboot, no. aspx extension shows up in the program assignment window when I go there to assign that extension to Firefox.exe. How can I make that new extension show up so I can define it?

See if this article answers any questions.
ASPX File (What It Is & How To Open One)

Right click on the file > Open With > Choose Default Program > Browse > navigate to the FF .exe > double click

Thanks for the quick reply. That is actually the very same article I read when I Googled aspx files to see what kind of file they are. It was then that I decided I wanted Firefox to open the file (since it is appearing from a website being viewed with Firefox anyway).

Thanks for the reply. The problem here is that the actual "file" never shows up anywhere I could use File Explorer to access it. The link in the site is supposed to print a claim form. When clicked, it tries to open the viewclaimform.aspx file from Firefox, which just appears as a blank window with the mention if it being viewclaimform.aspx file at the bottom. Then the computer, not knowing what to actually DO with an aspx file, makes its best guess and opens Windows Media Center. But from there I can find no way to view the aspx file anyway.

While all this is happening, the actual claim form file gets downloaded as a PDF file. which we can then access with Adobe Reader. But I am trying to get rid of the issue causing Windows Media to open. When it does, it does not display the aspx file. It just displays its typical startup screen.

I played with it some more, and got it to save a copy of a file named ClaimForm_PrinterFriendly.aspx to a folder. When I went there to look at it, the file name had appended itself to now be ClaimForm_PrinterFriendly.asp.html. I right clicked it and assigned it to Firefox. But when it subsequently tried to open, Firefox just displays the blank window this file created previously before it had opened Media Center. So I deleted the ".html" suffix, because the file extension I had actually created was just ".aspx". I right clicked it, and assign it to Open With Firefox. But it STILL causes Windows Media Center to open. It refuses to use Firefox.

If I close the browser, reopen it and log back into the site, and access the link again, it opens the blank window in Firefox, then opens Media Center on top of it. So I still have not stopped it from automatically opening Media Center. Note that before posting on the forum, one thing I had done is to remove ALL of Media Center's default file associations. It actually shouldn't be opening from ANY file. But it still does.

Perhaps the whole issue is being caused by the insurance claim website itself, and is overriding everything I am trying to do to change its result?

Still unsolved. I can't get Windows Media Center to stop popping open atop everything else, despite my having removed ALL its file associations.

I use "FileTypesMan" to establish file associations. It is a free utility and can be downloaded from;

http://www.nirsoft.net/utils/file_types_manager.html

Scroll about 3/4 of the way down the page and select the download link you require.

HTH

Open firefox, go to tools>options>applications tab. See if there's any listing for .aspx file and note its association.
Also, just to rule out if media centre is somehow interfering with it, type 'Turn windows features' in start button search field at bottom. You'll see an option 'Turn windows features on or off', click it and uncheck Windows media centre. Reboot if asked. Actually... reboot anyways.

Thank you for the reply. Windows 7 does make this more of a task then it used to be in XP, so I'll keep this utility in mind. However, I also read the post following yours at the same time, and it intrigued me so I went that route first, with success. :-)

Thank you for the reply! Your first suggestion instantly fixed the issue. I've been a Firefox user since the very early versions, and honestly never had cause to look in that "Applications" tab I guess, because this was a learning experience for me.

As soon as I opened that tab I could clearly see Windows Media Center was assigned as the app to open PDFs. It seems these assignments in FF work independently from whatever is set in the OS. I think what happened to cause this is that the PC is newly built, and I had not thought to install Adobe Reader yet. So when my wife had tried to access that form to print it, Firefox must have offered to try to open it with Media Center. She is not PC savvy, and didn't realize Media Center doesn't do PDFs, and she now says she thinks she may have clicked on a setting "always use this ( Media Center) to open this kind of file" when the offering was made.

Anyway, now that we had Adobe Reader installed, making the change was easy (in fact Reader even lists a "default" suffix when selecting what apps to use for opening a PDF).

Color us happy! Thanks to all of you for the help!