There's two different 0kb/s upload problems.

The more serious one (which does stop other people from uploading) can be fixed by moving the slider to 100%.

The other minor one is just a problem with certain uploads that aren't tagged as finished, so the GUI doesn't mark them as finished. But, they are merely visual nuisances and don't stop others from uploading.

Upgrading to the 2.6 beta should fix both problems.