Each time I get a new PC it's a pain to get eBS working with Java .. so I wrote myself a document on all the steps to verify whenever I wasn't able to install the plug-in. If I can only help out one fellow victim my mission is achieved :-).
I have Java7 installed, both 32 and 64 bit version (ignore the dutch in the picture). Then under internet options you add your websites to trusted websites.
At Configure Java (from version 7) you have to Enable Java and configure the exception site list.
Ofcourse you have to allow for popups and in some cases you still have to open the URL using Ctrl- to avoid the popups being blocked ..
Choose the settings, InternetOptions, tabpage Privacy. You can still have popup-blocking except for a list of sites. Add your site to this list if necessary.