Encountered this problem this morning, every time I try to submit a new post (quick reply + new reply):
Please try again. If you come back to this error screen, report the error to an administrator.
Weird thing is, all post submissions are successful in spite of the warning...but the error message is starting to get annoying. It's not limited to Winny, btw, I just met it again, here, while validating this post.
And, AFAIK, I'm not using any exotic tag whenever I post - merely "bold", "spoiler", "url", "color" and "underscore".
P.S. It looks like it's affecting the "who changed my karma", "notifications and email" and "show stats" pages, too, so I guess it has something to do with user data.