Excel 2007 error 'xx.xls cannot be saved in the current format'
 

Previously we worked on Office 2000
This has being uninstalled and Office 2007 has being installed

One user has this problem. Within Excel 2007, she opens a file that was
created in Excel 2000. When she presses save, she gets the message..

'??.xls cannot be saved in the current format. To save your changes, click
ok, then save it as the latest format'