Morten,
We'll have to test some more with blocked accounts. We did change how JFBConnect automatically logs user's in, and I could imagine a case where a continuous reload happens, which obviously isn't good.
There's a few options to work around the issue now, while we investigate:
1) Disable "Automatically Log Facebook Users In" option in JFBConnect, or
2) In Facebook, go to Account Settings -> Apps and remove your application. This will prevent the auto-login feature from triggering
Let us know if that doesn't fix the issue, for now, and we'll let you know what we come up with. There are a few other minor bugs we're working on for a 4.2.2 release later this month, and if this is something we can recreate, this will definitely go in that release as well.
Thanks,
Alex