Either your scanner is confused about where it should be scanning or there is a physical problem with the scanner.
Can you run copies from the flatbed and the document feeder like normal?
You can also try scanning from some of the default scanning programs on Win7 instead of the HP Scanning software. If the default Win7 software works fine then it is an issue with the HP Software install and you should reinstall to correct it. Paint and the Windows fax and scan application should be available to you to test scanning with.