Last night I noticed that my AdSense Notifier (Firefox add-on) wasn't displaying anything, and my custom reports wouldn't load. Today, this appears:

Too many concurrent reports
Your have too many reports in progress.
Please try again after some time.

When I go to Report Manager, I see that there are now ten "One-time" reports that are "Pending execution". I'd like to delete them, but there doesn't seem to be a way to do that until they have been generated.

I can still access my Overview, but prefer the additional information on the custom reports that I've created. Any ideas on how to fix this?