I have a java application that works perfect on a fresh installation
(xp). However I'm trying to run on a computer thats had load of rubbish
installed before.

When trying to run my app I get the error message  "main class not
found" therefore it must be a linker, jvm or similar problem. I can't
wipe the hard drive and start a fresh install because its a customers
demo computer. How can I remove all traces of previuos java
installations? I think there may be conflicts. Any help or pointers
would be apreciated.

Thanks in advance