Java problems

I have problems with Java in Safari. Earlier when I played Java games, I didn´t have any problems with Java. But now when I play game that requires Java, only a blanc windows show up. But when I get back to my startpage, everything is normal. This happens to all Java games I play. Only a blanc window shows up. I have had this problem very long now. I have updated the latest version of Java, but it doesn´t seem to work.