Hi Martin, which particular folder and filename are you saving to?

Are you possibly trying to save it to one of the folders that Windows 7 protects from modification?

Also which particular command are you using - "Save As" or "Export" ? The "Save As" will write everything out to the file name you pick, while doing an "Export" only writes out selected objects. If you do an Export and do not currently have anything selected then there will be a selection step where you'll see a prompt in the upper-right corner of the main window asking you to select objects to export and the file will not actually get written until you make the selection and right-click or push "Done".

- Michael