Image Scrambles

[GreenXIII]

I have downloaded a video from a website, encoded with divx 3. In many parts of the video the image scrambles, getting very pixelated, then comes back to normal. Virtualdub indicates an error message in the more severe scrambling parts, saying it's corrupted data. I downloaded the same file from another server, now compressed by winrar, and got the very same errors, which means the data was not corrupted while I downloaded the video. The problem was already there.
What should I do to prevent these scenes from scrambling?

[setarip]

If these were downloads of illicit copies of commercial media, chances are they are intentionally fouled up...

[GreenXIII]

No, I don't believe that's the problem here.

[setarip]

And why is that?

[GreenXIII]

People, I think corrupted data in a video file is a very common problem, so if anyone can please help solve my problem instead of making silly questions I'd be glad.