The problem is cos you've been pressing the prtsc button lots, it's been taking lots of images and storing them in the clipboard. When you press paste, it pastes the last one you tried. Your evil nestle one is probably halfway down the list.
Soooo. You have some choices here.
Lets try going to Word, clicking Edit & then 'Office Clipboard'. You might need to press the little downwards double arrows to expand your menu before you see the 'office clipboard' option.
This should show the contents of your clipboard, from here you can choose which image to paste. If you can't see it clearly then you can select 'clear clipboard' and then go back to mumsnet and do it again - BUT ONLY PRESS THE BUTTON ONCE!! Then it will work nicely.