You've got more than one version of Java installed on your machine, which is perfectly OK -- but you have to keep them straight. You've compiled your classes with JDK 1.5, but are trying to run it with an older version.
You can either find the offending copy of Java (some older JDKs liked to put a copy of java.exe into C:\WINDOWS\ or some other such silly place) and delete it, or you can modify your PATH environment variable so that the JDK 1.5 installation location comes before the location of this older Java version. Whichever is easier for you.
Thank you ! Thank you ! Wow, I'm an old RPG programmer trying to learn JAVA for a new job. It's quite a culture shock for me with all this "newfangled" stuff. I uninstalled the older version and it works fine. I was really stumped so your suggestion got me going again..for now...I may have to use this forum again. Thanks for the help ! Brian.