I suggest you consider downloading a different search engine, such as Firefox, Safari, or Chrome, as the engine you're using right now might'n trust these downloads and is probably blocking them through your firewall, or security settings. I'd had this problem in the past myself, I think you should try running Astrill through Administrator, though, before you consider downloading and installing another engine that might not work as well.
I know I've seen posts like this around some other forums I'm part of and mediafire's links have been known fr crashing/breaking. If you don't want to do the above, try waiting it out a few days until mediafire is under control again.
Hope I was in any way helpful. ^^
