"Access Denied. Contact your administrator"

Hello,

We are a small company using WindowsServer2008R2 Enterprise software for our file server. Users are using Microsoft Office 2010 on Windows 7 Professional. All users have similar permissions.

When I open a file from file server on my computer, and edit -> save -> close it, after that neither me nor other users are able to open the file. We all get error "Access Denied. Contact your administrator". 

Note that if OTHER users do the same (i.e. open a file from file server on my computer, and edit -> save -> close it), we dont get the same error. We all are easily able to open the file.

Please suggest a solution urgently.

Thanks