This seems to be a persistent problem, but on the several posts I've seen here, no one seems to have posted a working solution. Adding it back to the community in hopes someone is using NextGen and it works for them.
I can create a gallery, but cannot use the flash uploader to add images to it. I have to disable the flash loader and upload them one at a time. I've deactivated all of the other plugins, and have the same problem. I've tried it on a different computer and same problem.
As often as I see NextGen recommended as a gallery plugin, surely this isn't a problem for most users. Anyone that has gotten the flash uploader to work, please let me know how.