What version of Java are you using? If you've been using 1.6.0_01 or 1.6.0_02, try the latest update. Download the offline installer & remove your current Java version(s) before you install this one.
Java SE Downloads

If that Java version gives you trouble, try this older one. Again, download the offline installer & remove any other Java versions before you install.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11