I cannot get Juniper Host Checker to run since the latest Safari update

I have Safari 6.0.5 on OS X 10.8.4 and java 7_25. Ever since my laptop installed updates at the weekend, I can't get HostChecker to run. This is a java app that runs and checks out the suitability of my host to connect to my companys network. It was working fine Friday. So frustrating as I can't log in and work. I tried the article about switching to use java 6 but no luck - safari freezes right after I select "Don't block" when it starts running HostChecker. Any ideas please to help me stop getting stressed? Thanks 🙂