Export to excel was previously not working for clients that were using Office 2007 because we we are using claims based authentication. A few days ago a few clients noticed that the export to excel functionality was working. Is there a reason it would suddenly start working? I didn't see any Windows updates that might have fixed this issue. Any ideas???
It may not have been working if there were issues with the Excel Calculation Services, which may have been fixed (permissions or otherwise). Has The ECS been stopped recently or reported any errors in the Event Log?
Also check what security IE is set to for your SOE. Make sure IE has the site set to trusted.