Admin Products page bug (page not found!)

Hi, has anyone ever had this problem with some of their page's in the dashboard not showing.
Products page & Extensions modules, shipping, payments etc...

My Products page has a bug, it says at the top of the page "Page not found!", but if I scroll to the bottom the page
is loaded correctly. It's as if the page has loaded twice.

I would include a screen grab, but don't see the option too.

I'd appreciate any advice, thanks.

Version 1.5.6.4

Below the Posting Area, you have an ATTACHMENTS Section, where you can upload images.
It's the only way to show, what's missing or wrong.
Ernie