Can't open Excel File!

Hi,

I'm new w/ MAC, in fact I don't have one. Actually this is a problem on one of my client. My client had a macbook and an office 2004 is installed. He bought a new macbook. What they did is copy the office 2004 and also the office files from the first macbook to the new one.
In fact there's no problem in using the office 2004, it works very well not until both macbook is on the same network (wireless network) and either one of the macbook open an office application like excel files first, the second one can't open the application.
The error message states that it cannot open because the file is in use. They're not sharing a single files, they have their own files stored on their local drive.
Please can anybody explain why is it happening.

 

yes. so what if i will install the same installation cd (the one they used from the old macbook) to the new macbook? is there any difference from simply copying from one mac to the other?