[Plugin: NextGEN Gallery] Loading many images, but only one is stored.

I use the flashbased load images to load many images at a time. The user interface shows loading all images one by one, but the final result is only one image stored in the gallery. I use a fast (20 Mbit/s) fiberline to load the images and the loading is fast. NextGEN is set up to resize the images, which is a rather slow process. Can it be that the loading is to fast for the server to process?

http://wordpress.org/extend/plugins/nextgen-gallery/