i would guess it's due to the joins:
bd.SORTUSER_EMPID = ed.[Employee ID]
i think maybe one column is an integer or numeric column, and the other is varchar?
due to data type precedence, the varchars are being converted to integer, and some values are not actually numeric:
try converting to a varchar join for teh data type, since it's being implicitly converted anyway?
CONVERT(varchar,bd.SORTUSER_EMPID) = CONVERT(varchar,ed.[Employee ID])
Lowell