Hello, I have the same problem on my laptop with Win7 64 bit.
I can not set the default program for opening video files nor even open them with the program I want.
When I open a .mp4 file, it opens by default with VideoLan. But I want to open it with Media Player Classic (MPC).
So I make a right click on the mp4 file -> Open With -> Browse -> I select C:\Programs\Media Player Classic\mplayerc.exe and then I click "Open" and then the MPC does not show in the programs list (it should appear in "Other Programs") section.
I have no idea how to solve this problem, can you help?
Very strange, it says my user is Administrator but when I enter in "Change your account type", it says that it's a standard user and I can't change it to Administrator.
If I check "Administrator" radio button, then the "Change Account Type" button will become gray, and I can only select the other button - "Cancel"
Also when I type in cmd "assoc .mp4=" it says "access denied" so probably my account is not Administrator. Not sure though.