I had solved the problem, reason was in urlrewriter.net component, as you suppose, seems that it is handling request from your uploader. Solution is not use query string parameters on page where you wonna to have uploader, else url rewriter will break uploader......

But i remember that version 1.0 and 2.0 was working corrent with url rewriter and diferent query parameters....

Hope in future versions of urlrewriter or your uploader this issue will be fixed....