#REF!

Can anyone help me here?
Created Consolidating spreadsheets using SUM(BEG:END) tabs in workbook. File is saved on a network drive. When opening the file at another person's computer, all cells come up #REF!. When I return to my own computer and reopen the same files, all formulas are intact and work fine.
Can someone tell me why this happens and is there a setting to correct/prevent this from happening?
Thank you!
Fred