Your Java's pretty old, try updating it. Use the JRE offline installer & remove your old Java version before you install the new one.
http://java.sun.com/javase/downloads/index.jsp

Are you checking files with Bitzi before download? If other users've rated the file, you'll get some idea of content & quality (there are some shockers out there that aren't worth downloading). It's possible that you've found 2 crappy files!
How to use Bitzi

That other thread I linked to suggested a bug in the Beta versions 4.13.0 & 4.13.2. I had no trouble with the 4.12.3 as far as I can remember. If you want to try a different version, download the latest stable release or Beta basic...test it out!