Excel question

[Wresh]

Seeing if anyone here might be able to help me on an Excel issue. I've never seen this happen before.

I have a large spreadsheet (kind of a "master roll-up") that utilizes VLOOKUPS to grab information from about 10 other spreadsheets.

When I open the "master" I have no problems - all of the formulas get the information properly from the referenced spreadsheets; however, if I then open one of the referenced spreadsheets with the "master" open, all of the formulas with that referenced file Error out with #REF!.

Before opening the reference file here is what the formula looks like:
=VLOOKUP($A165,'S:\!2011 OBU Holiday Readiness\Daily Stand Up\[Logistics.xls]Sheet1'!$A:$BE,MATCH(E$3,'S:\!2011 OBU Holiday Readiness\Daily Stand Up\[Logistics.xls]Sheet1'!$3:$3,0),FALSE)
This is evaluated perfectly - I am seeing a value of "25" which matches the "Logistics" spreadsheet.

If I then open the "Logistics" spreadsheet I get #REF! errors accross the "master" and the Formula now looks like this:
=VLOOKUP($A165,[Logistics.xls]Sheet1!#REF!,MATCH(E$3,[Logistics.xls]Sheet1!#REF!,0),FALSE)

These files are located on a network/shared drive.

[Lonskils]

Might be an issue with permissions as that if you open it the master believes it is being used by someone else and therefore isn't available for reference.