Word and Excel Corrupt in File Server

Dear All,

Anyone can help? suddenly in one day all file (only office file such as word .doc and excel .xls 2003) in my file server (Windows Server 2003 No Service Pack) is become corrupt (most messages is unrecognizable file format) other file like txt, jpg, mp3, etc is just fine

Anyone ever has experience the same problem?

Is it a virus? (since there’s no threat detected on the files)

Please help, thousand of file in all folder (in one partition) all corrupt..

Thanks,
Indra