We were made aware of a bug on the forum following the header/footer updates a short while ago. We're sorry for the inconviencie here, it was a very frustrating bug I know!
Pleased to report that this should now be resolved. We've fixed the cause and cleared the forum cache which should ensure all users no longer seen the annoying behaviour of scrolling on press of your return/enter key.
If you do, try logging out and logging back in (our version of turn it off and on again).
If this doesn't fix the bug, please reply below or send a PM,