I made a mistake of associating .mp4 files to open with Windows Media Player 11. I downloaded the "unassoc.zip" file from An Utility to Unassociate File Types in Windows 7 and Vista and followed the instructions. However, the "Unassociate a File Extension Type" button is gray out. Is there another way I can unassiate .mp4 files from WMP?

I'd appreciate any suggestions. Thanks!

Yes, open up default programs from the start menu, then click the "associate a file to a program link" in the window that appears, then scroll down to .mp4 and click change program. Navigate to the Windows Media Player .exe.

Hi Frostmourne,

Sorry, I guess my post wasn't clear. I don't want the .mp4 files to be associated to anything. It turned out that Windows Media Player does not play the .mp4 files so I rather un-associate the .mp4 files from Windows Media Player.

Thanks!

Then, try right-clicking the program and running as administrator since the software has to access the registry which it can't without permission.

Nope, that didn't do anything. Help!

Open up a cmd prompt from the search box in vista by searching for cmd, right clicking on the icon and selecting run as administrator. It has to run with higher priveleges. Then follow this:

Remove File Extension Associations and Unassociate File Types in Windows Vista - Tips & Tweaks

Originally Posted by Frostmourne

Open up a cmd prompt from the search box in vista by searching for cmd, right clicking on the icon and selecting run as administrator. It has to run with higher priveleges. Then follow this:

Remove File Extension Associations and Unassociate File Types in Windows Vista - Tips & Tweaks

I tried unassociating the extension file using cmd prompts assoc .mp4= followed by ftype WMP11= but those didn't work for me.

I went back to the "unassoc_1_4.zip" utility that I downloaded from An Utility to Unassociate File Types in Windows 7 and Vista and clicked "Delete file type" button (I think this deletes file extension from the registry) since the "Remove file Association (User)" button was grayed out. This works! The .mp4 files are no longer associated to Windows Media Player and the WMP icon is also removed. Now when I click on any .mp4 file, Windows asks me to choose a program to open with. This is exactly with I wanted!

Thanks everyone for your suggestions!

Originally Posted by delphin

Originally Posted by tropicalchic

Hi Frostmourne,

Sorry, I guess my post wasn't clear. I don't want the .mp4 files to be associated to anything. It turned out that Windows Media Player does not play the .mp4 files so I rather un-associate the .mp4 files from Windows Media Player.

Thanks!

Open regedit,Expand Hkey_classes_root. Find .mp4 key and delete the entire key.

Restart your computer.

Let me know the result. (Restart is must)

Hi Dephin,
I think your suggestion would work. But I didn't get to try it since it was posted after I have already resolved it using the unassoc_1_4 utility as described in the previous thread. Thanks again for your help!