ACCESS ERROR "..OR IS TOO COMPLEX TO BE EVALUATED..."

I have inherited a couple of databases over here in Warranty and one of them has a minor bug that I can’t seem to find. I have a drop down box on a form, that runs a simple query from a single table, and when we select drop down for August 2011 it will not finish running the query ?  It gives this error message ; again all we do is select the month in the drop down ? I have looked at all data in table see nothing weird or corrupt in the  data and it will pull all other months just fine ??? any advice??  Here is the Qry statement;

SELECT Format$(Resolution_Result_tbl.Date_of_Record,'mmmm yyyy') AS [Month]
FROM Resolution_Result_tbl
GROUP BY Format$(Resolution_Result_tbl.Date_of_Record,'mmmm yyyy'), Format$(Resolution_Result_tbl.Date_of_Record,'mm')
ORDER BY Format$(Resolution_Result_tbl.Date_of_Record,'mm') DESC;