Hello,
I have the same problem, but on Windows XP, with FF 3.5 (I also try on OSX with FF3.0).
In fact, I never found a way to use the java uploader
I'm using Phocagallery 2.5.6 and each time I try to use the java applet, I get the same error after minutes of loading :
Exception : java.lang.ClassNotFoundException: wjhk.jupload2.JUploadApplet
Any idea how to fix it ? Is JumpLoader a good "bypass" solution ?
Best regards,
mhammout
! UPDATE !
Finally, I installed Joomla Flash Upload (
http://www.tinywebgallery.com/en/tfu/web_jfu.php) and it saved my life

even if I have first to upload the images before creating the galleries...
Note for admin : maybe you could add this component (I mean the flash) to PhocaGallery natively ?