Office 2007 Help Source Stuck in Off-Line mode

The Help function in Office 2007 applications have the option of searching
either on-line or off-line. The option is set via a control in lower right
hand corner of the Help screens. In all of my Office 2007 Apps, which are
running under Vista, only the off-line option is available. i.e. When I
click "Show Content from Office Online" the connection status remains
"offline". I suspect this is a simple set-up parameter but can not find it.
Any suggestiion greatly appreciated.
Jim