Using a corporate SharePoint site and access with IE 8 and running Office 2010.

Trying to open Excel XLSX files right on the SharePoint site and get error "The file you are downloading cannot be opened by the default program.....". I'm then foced to SAVE the file instead of opening. I can open xls files on SharePoint but am forced to save xlsx files.

Windows Explorer file types is set to use Excel to open xlsx files.

Any ideas?