I had this problem for few months, Internet is full of data for Macintosh, not much for PC

The link below leads to simple but elegant solution.

< http://www.planetamd64.com/index.php?showtopic=36759&mod e=linear>

In short: Microsoft Office 2007 - Groove aplication creates a conflict with Photoshop CS3. just uninstall Groove and off you go, all is working perfectly.

Hope that helps.