UT blocks when repository are not found

[alesmuc]

On my Ubuntu 12.10 I try to install Stormcloud from "Applications" tab.
I select the "source" and I click "update"
The window "updating the cache" appears, but doesn't find the repository, these are details:

W:Failed to fetch http://ppa.launchpad.net/cooperjona/stormcloud/ubuntu/dists/quantal/main/binary-amd64/Packages 404 Not Found
, W:Failed to fetch http://ppa.launchpad.net/cooperjona/stormcloud/ubuntu/dists/quantal/main/binary-i386/Packages 404 Not Found
, E:Some index files failed to download. They have been ignored, or old ones used instead.

But when I click "Close" the windows doesn't close (but I can still move it) I have to force the exit from Ubuntu Tweak.

Screenshot attached