A new definition for the microsoft windows defender is available.
This is not so spectacular, but some people wanted to update this manually instead of doing this automatically.

Follow the link above and download the file. You will notice that the file itself is called mpas-fe, which you have to double-click in order to update Windows Defender.
At this microsoft site there is a detailed description of that file. You can always download the latest definition files from the download link above, so it would be a good idea to bookmark this post. The files will be replaced by microsoft as soon as there is a new definition.

Microsoft Windows Defender is a useful little tool to check your PC for viruses, trojans and other forms of harmful files. It’s one of the several improvements that make Vista a better Windows than XP. Enhanced security is always a big plus!