SYMPTOM:
In Strategy Web 10.0, when exporting a Report Service document from Presentation mode to Excel format, a warning message as the one below will pop up, even if no changes have been made to the document. The notification will pop up regardless of weather the user has the "Use Office" privlege or not.

Message in presentation mode.
The document has been changed. If you do not save it before exporting, your changes will be lost if you refresh it using Strategy Office.
CAUSE:
This is an identified defect in Strategy Web 10.0
ACTION:
This issue has been addressed in Strategy Web 10.3. Upgrade to this version to take advantage of this fix.