Comment 5 for bug 1030544

After shutting down and later powering up the machine that experienced the problem, I have been unable to reproduce it.
It was reproducible before shutting down though, and came and went as I removed and re-inserted the line mentioned above.

I think I need to find why a URL needed to be fetched at all, rather than trying to block it in cssutils.
Perhaps there are still some upgrade checks that need to be removed from Calibre.