To ensure that linkages in my spreadsheet will work for other users on our
shared folders, I have used the full pathname, or UNC name, in my formulas.
It works fine for VLOOKUP, but for some reason I get the #VALUE! error when
using SUMIF in Excel 2007. I'm not sure what I'm doing incorrectly, or
simply that using the UNC name will not work in SUMIF.

Here's a sample of the syntax:

SUMIF('\\hyperdisk\data\accounting and finance\budgets\2008 CFO
Report\[PriorActual.xlsm]January'!$F$2:$F$99999,$B42&$C42,'\\hyperdisk\data \accounting
and finance\budgets\2008 CFO Report\[PriorActual.xlsm]January'!$G$2:$G$99999)