Unable to utilize spreadsheets with formula's after upgrading to windows seven from xp

I have multiple spreadsheets that have formulas pulling from other spreadsheets that I use for daily, monthly & annual reports. After upgrading to Windows 7 from Windows XP these spreadsheets are no longer seeing the formulas if I open multiple spreadsheets at a time. This is a problem as my monthly and annual spreadsheets need to pull from multiple workbooks in order to give me monthly and annual totals. I have macros set at "Enable all macros" and have added the file location in "Trusted Locations". What else do I need to set in order to work on multiple spreadsheets at a time and the formulas pull data as needed?

Thank you,