Managing websites

In Safari > Preferences > Security > Allow Java Manage websites... is it possible to add websites manually? Websites using Java work in Safari, EXCEPT for one on my machine. On my wife’s MacBook (10.7.5) it works. What files should I be looking at?

I HAVE installed the latest versions of Java & Flash Player, and everything is enabled. I tested Java on the Java Test page, and it is running properly.

Thanks,

Klaus