On the "summary" sheet cells C6:C9 and E6:E9 have COUNTIF formulas referring to other pages in the spreadsheet, but do not calculate in excel until you double click the formula, then hit enter.
Created attachment 11252 [details] zip file containing spreadhseet with countif error example
Retested OK in 3.1-beta1 This was probably fixed due to bug 44675 (var-args param count issues)