excel does not load

[mangoa]

When I click on the icon of an xls file, Excel itself loads but it does not load the document. All my xls icons show an undefined icon, so they do not have the excel icon. In the control panel the default program is 'excel (desktop)' I am not sure what that 'desktop' means. If I click on an xls icon and do 'open with' I am again presented with the Excel (desktop) option. Even when I select that option the problem persists.
So, to recap, when I click on an xls icon, excel the program loads but does not load the file. I have no problems loading the file from within excel.
I recently purchased and installed Office 13, but left Excel 2010 on my system. Yesterday I uninstalled Excel 2010 since I felt I wouldn't need it any more and that's when this problem surfaced.
Any help would be greatly appreciated.