This errors will occur when Excel is not installed, or more likely, the wrong version of Excel is installed.
According to Microsoft, there are two versions of Excel 2010; “Click to Run” and “Regular”. The “Click to Run” version does not install the necessary registry entries used by GDXXRW and thus GDXXRW will fail. The following article http://support.microsoft.com/kb/982431 explains how to un-install the “Click to Run” version and install the “Regular” version.