A little bit lost adding a third criteria to the following formula:
=SUM(IF(MOD(ROW('2008 Errors'!$A$3:$A$3000),10)=3,IF((YEAR('2008
Errors'!$A$3:$A$3000)=2008)*(MONTH('2008 Errors'!$A$3:$A$3000)=1)*
(LEN('2008 Errors'!P3:P3000)-LEN(SUBSTITUTE('2008
Errors'!P3:P3000,"KT",""))0),1)))

too add that a further range of cells ('2008 Errors'!B3:B3000) with the
criteria "Fax" occuring in them (and in the month of January in A3-A3000 and
"KT" in P3:P3000 as detailed in the formula above) would then produce a
cumulative result as the obove formula does for the two criteria...getting
mixed up with my brackets etc
Cheers