in reply to
Random extracts appended to end of posts after create?
I see you've found this is a reported bug: Re^6: Random extracts appended to end of posts after create? (data). Let's hope it's fixed soon.
I've been getting the same problem with Opera on Mac OS X. Deleting the garbage at the end doesn't seem to work but replacing it with a newline does (although I occasionally have to do that a couple of times to make the garbage go away). Maybe that workaround will work on your OS as well.