check the thread that announed the new beta, lots of others are too... A kind soul has put a copy of the software http://www.kmcreaxion.com/temp/ParallelsDesktop3094Macen.dmg
I download with Safari, and if a download times out, one click attempts a restart, and usually continues from where it left off. Sometimes it will fail again, so I just keep restarting until it works. I've never had a problem with that technique.
thats because you get a corrupt download .. The Parallels servers are/were having issues. I had the same problem earlier and used the alternative site to download and all is fine now.