~5 seconds after a new download begins, something goes wrong with the system for about 10 seconds.
I can't open a new shell (!!!)
ktorrents GUI does not update
i can't open new programms in the shell

It's hard too explain, but maybe this picture helps: http://imagebin.ca/view/xtAuxi3C.html
red: upload
yelloq: download
You can see, ktorrent freezes after the download starts. After some time everyting works again.

I think i can still use firefox if it was open before the download begins.

This does NOT happen everytime!

I am using debian testing with some older kanotix kernel.