At first I thought it was the Blocklist plugin causing problems, but even after disabling the Blocklist plugin the problem continued.
After trying various different things, I seemed to track the problem down to Deluge's update notifcation.
If I turn off the setting that says: "Be alerted about new releases" then Deluge starts fine. However if I activate this setting then Deluge starts hanging when it's launched. It doesn't happen straight away, it's maybe two or three launches later that the problems start.
I have tried deleted the entire deluge folder in ~/.config but it made no difference. So then I tried launching Deluge from the command line. It took 5 launch attempts before the problem reoccurred and the error message in the console was:
Has anyone experienced a similar problem?Network error while trying to check for a newer version of Deluge
Incidentally, (I don't know if it's related) but I've been having loads of problems with this forum timing out when trying to access pages.