Please Help me with Java applet program

I have a dell inspiron 8600 notebook. I recently downloaded the latest  version of JAVA JRE software from www.java.com  However, whenever i tred to chat on some websites, I keep getting an error message which says Java applets failed. As it's suggested on the Java help page, i tried to enable the JRE through the web browser, enabled the JRE thru Java plug-in controll panel and also cleared the web browser cache. I uninstalled Java and reinstalled hoping it would work but so far no luck.  I am not really a computer person. I would really appreciate it if anyone let me know what i am missing?