Excel 2011 is not opening files?

My problem is that I cannot open up Excel files on other computers within my company's network. If I create an Excel file on Computer A, then I can open it on Computer A, but I cannot open it from Computer B. I am able to copy files from Computer A onto Computer B's desktop and then open that Excel file. But I do not want to have to resort to transferring all files to Computer B's hard drive.

Here is the error message I receive when trying to open the network files:

<the folder which the file is stored in> could not be found.

Check the spelling of the file name, and verify that the file location is correct.

There are three things to note: 1) we can still open Microsoft Word for Mac files just fine; 2) the folder that the network files are stored in is called 'server', could that be part of the problem???; and 3) we are using Microsoft Office for Mac 2011.

We have updated Excel and all of the other Office programs, and creating an additional administrator account does not help whatsoever. Please help us, we don't like running the risk of losing important Excel data.

Best regards,

Peter