How do you disable "File not found" message box?

I have a scheduler running that creates a Excel file every day with a unique name, such as HD1, HD2, etc. These files are on a networked drive. I have another Excel spreadsheet that has links to these files that have not yet been created so I receive the "File not found" message box. Is there a way to get Excel to stop displaying the "File not found message box? Is there a formula so Excel will ignore the fact that it's source does not yet exist? I have tried iserror but still get the "file not found" message box and then will display the TRUE value. I am running Excel 2000.