could not open Excel while start dashboard

Get this error for all xlf documents.

"Could not connect to Microsoft Excel. To prevent further data corruption, the program must close."

try these,

kill excel process, not working,

run as admin, not working,

change name, unzip, run excel, not working.

not only for my own xlf, but also default template. any attempts to connect to Excel will cause this exception.

was worked well five month ago. Please help.

OS: Win 7 64bit

Office: 2010 32bit

DD: Ver: 6.0.0.0 Build, 14.0.2.364.

Years of work lost, Please help

PS. Just reinstall DD, still not working.