Excel file can not be accessed

when you're open an excel file or word file, perhaps you found this problem:

'????.xls/????.doc' cannot be accessed. The file may be read-only, or you may be trying to access a read-only location. Or, the server the document is stored on may not be responding

I have searching this problem to fix my files, but microsoft themselves just said that it was an error because blah blah blah... no solution to open my important files...

fortunately, I have an open office installation on server (the server is Win 2003 server, but no office license, so I installed open office there)...
I tried to open the file using openoffice calc, and it works! (looks like MS advertising slogan)...
The corrupt excel file can be opened by openoffice calc and I can save the file into a new excel name . and this new file is okay to be opened by MS Excel.

so, if you found this problem just try this one:
- open the file using another application (non MS)
- save to another new MS common name.

FYI, my open office is 2.1 version...

shall we install open office in all our computers now?