Having problems opening an xlxs file generated in Windows Office 2007 with Mac Office 2008. Mac Office keeps telling me that the file is corrupt. I can open the file just fine on my Windows machine in Office 2007....no dice on the Mac. However, if I Save As a regular .xls file, it works OK. I have many files that I need to use on my Mac that were generated in Windows Office 2007. Aside from opening all those files and re-saving them, is there anything else (easier) that can be done? Can't they natively open in Mac Office 2008?