Here's a list of a few bugs/issues that commonly have tickets submitted for, and their fixes.
The request was invalid and has been discarded.
This is caused when users who never or haven't recently validated their email address try to post a shout or comment.
Solution: This can easily be fixed by validating your email
I just changed my avatar but my old one is still showing
The site can sometimes take up to 15 mins to update the image/cache.
Solution: Check the site again in 15 mins. If it's still causing issues after that, please submit a ticket.