Can't read m4v video files since I've installed Itunes 10.4 update.

Hello,

I've bought video files on Itunes Store which were working perfectly so far on my macbook pro.

Since I've installed Itunes 10.4, when I launch m4v files, I just have a black non active screen, no message, nothing else.

Other video or audio files can be read.

I'm using mac OS X 10.6 so it's supposed to work.

My other mac (Imac) which is using Itunes 10.3 can read these m4v files without any problem.

So I tried to get back to Itunes 10.3 (for my macbook pro) but I can't cause the Library has now been created with a more recent version of Itunes.

Please tell me what should I do...