IIS 7 web server changes my Office documents after GoodSync uploads them via WebDAV. Why?
SharePoint DAV server (part of IIS 7) adds additional XML data to files which are Office documents such as .PPT, .DOC, .XLS. This is not something that GoodSync is doing and not something that GoodSync can change. You should find a setting in IIS 7 to turn off this feature or ask Microsoft support how to turn this off in IIS 7.