I've the same problem... HELP!!!
A similar problem here. The Download Assistant is unreliable at the moment, and official Adobe support can only suggest redownloading the source package with the usual "clear the file, try again" advice until they improve the service. Frustrating, but if you download on a fast connection without interuptions (so no pausing, and best to minimise background application activity) you should be successful. I'm one application down, and three to go (with over six failures over two days).
Needless to say, as a customer I am frustrated that I can not access purchases software from the vendor in an era of lightning fast torrent networks and growing open source alternatives. Product delivery should be a priority for Adobe.