I had to rename the 'npdeploytk.dll' in both locations (in the Sun Java program folder and Mozilla Firefox program folder).
.FaZio93., the said file indeed is present here:
C:\Program Files\Mozilla Firefox\plugins
but there is no references in the Registry as a Firefox plugin
Where you can see it in Firefox as a registered plugin?
I can see MS .Net Framework Assistant (ClickOnce), which is silently installed by Framework 3.5 SP1 (that's known fact), but I cannot find Java Deployment Toolkit in Fox
Am I missing something ?