Floating Point Error - Order By Mystery

I'm having a problem that I think is due to corrupt data. Depending on
the column I use in my order by clause two problems are occuring.

1. No results are returned and I get this error:
A floating point exception occured in the user process.

2. Results are returned but there are a different number of rows depending on which columns I use in my Order By clause.

Examples
SELECT * FROM SymbolStats
ORDER BY calc_date, symbol

Returns - 12207 rows but only includes one of the 25 dates in the table.

----------

SELECT * from SymbolStats
ORDER BY current_hv

Returns - 0 rows.

----------

SELECT * from SymbolStats
ORDER BY average_hv

Returns - floating point error

With more conditions in the WHERE clause the number of results returned varies greatly.

The
fact that different numbers of rows can be returned from the same query
only differing in how they are ordered seems like a bug.

Does this sound like corrupt data? If so, what are the best methods for fixing it?

Thanks,
patrick