Java 3D problems

[Atrus Greyor]

I am able to write and compile J3D programs. But when I try to run them I get this error message:

Registry key 'Software\JavaSoft\Java Runtime Environment\CurrentVersion'
has value '1.3', but '1.4' is required.
Error: could not find java.dll
Error: could not find Java 2 Runtime Environment.

I have Java SDK 1.4.2 and these error make no sense to me. What should I do???