Overflow error

I keep getting an overflow error on a the below:

SELECT Query1.RCTrack, Query1.RCDate, Query1.RCRace, Query1.Horse, Sum(Query1.RCWT) AS SumOfRCWT, Sum(Query1.NFIN) AS SumOfNFIN, Sum(Query1.RWNF) AS SumOfRWNF, Sum(Query1.RWBEYER) AS SumOfRWBEYER, Sum(Query1.AdjBeyer1) AS SumOfAdjBeyer1, Sum(Query1.AdjBeyer) AS SumOfAdjBeyer, Sum(Query1.NFC) AS SumOfNFC, Sum(Query1.RWFC) AS SumOfRWFC, Sum(Query1.SPEED) AS SumOfSPEED, Sum(Query1.NODDS) AS SumOfNODDS, Sum(Query1.RWOP) AS SumOfRWOP, Sum(Query1.RWSP) AS SumOfRWSP, Sum(Query1.RWPUR) AS SumOfRWPUR, Sum(Query1.RWWT) AS SumOfRWWT, Sum(Query1.RWDST) AS SumOfRWDST, Sum(Query1.NPOST) AS SumOfNPOST, Sum(Query1.ADJLENS) AS SumOfADJLENS, Sum(Query1.RWFINLENS) AS SumOfRWFINLENS INTO [SUMS OF FACTORS]
FROM Query1
GROUP BY Query1.RCTrack, Query1.RCDate, Query1.RCRace, Query1.Horse;


There are 712,000 rows in this.  This is Tracks G through I.  In tracks A through B, I did not get an overflow with the same code.  A through B has 1,310, 000 rows.