image data corrupted

hi i have this problem on my mac that whenever i try to open the dmg for unity 4.0.1 an error comes up saying “image data corrupted” any help?

This means that the dmg is corrupt. On my machine I get:

% ls -l unity-4.0.1.dmg
-rw-r--r--@ 1 graham  staff  1055785582 11 Jan 10:02 unity-4.0.1.dmg
% md5 unity-4.0.1.dmg
MD5 (unity-4.0.1.dmg) = e8bf1cc24c40bf5e7edad1f4bdd1c9b7

If you get anything else, then try re-downloading. If you are sure that you are getting a fresh copy, and continue to get something different, there is a very small possibility that the server you are getting the download from has a corrupt copy. (We have multiple servers around the world and your download is served by the geographically closest server. If that server does not have a copy, it fetches it and caches it and then passes the cached copy on to you.) If you continue to have problems, just let us know where the world you are and we can flush the cache. (This happens very very very rarely, but can happen.)