Redirect URL not working with Java applet in Firefox 2.0.0.11

The Redirect URL appears to not be working using Image Uploader 4.5 Dual (Security Fix) with the Java applet in Firefox 2.0.0.11. The JRE version in my browser is 1.4.2 (I realize this is not the latest, but I need to test this version as it is the oldest version most commonly in use across the Internet). The Redirect URL does work with the ActiveX control in Internet Explorer 6. I am calling the same web pages from the two browsers. The file does upload successfully using both browser/control combinations mentioned above -- it's just the post-upload Redirect that is not working. I have not tried other combinations of browser and applet/control, as I am just deploying the Image Uploader product on my web site, so I have not tested very extensively. Does anyone else experience this behavior? Do I need to set some additional parameters specifically for the Java applet, so that it will redirect?