If you haven't already, could you try updating to the latest 6.0 Beta, available here?
http://www.displayfusion.com/Download/Beta/

If you still have trouble, could you try disabling the following options, one at a time to see if they make a difference?

• Settings > Window Management > Enable maximized window dragging
• Settings > Window Management > Show a ToolTip when moving or re-sizing
• Settings > Window Snapping > Both "Enable Window Edge Snapping" options

Thanks!