Java applets do not work anymore on my pc

I have tried firefox, internet explorer and google chrome but the applets do not show anymore. Also the browsers freeze when I load the pages. This happened before but not with all the browsers. I have no idea what I can do to fix it. I will try to look up what the problem might be.

edit :

I could not find any information yet. I have also tried reinstalling the java runtime. This did not fix it. I also tried another computer and this gives the same error. Also older applet that used to work did not work anymore. I get a magic number error with the applets when they do load. I hope this problem will fix itself in the future. As I have no idea what to do.