How to resume downloads without restarting from zero?

Hello,
When I download something (I tried with TV show and Podcasts) and I pause the download(s), I can't resume from where I left off. The download restart from zero, even if iTunes was always active and the computer didn't go to sleep. It looks like the "Pause All" and "Resume All" buttons should be named "Cancel" and "Restart" instead.

I have iTune 7.4.2 (4), Leopard 10.5 and Safari 3.0.4 (5523.10).

Thanks for your help