Strange Query Error

Hi, I am wondering if anyone has ever encountered this query error before and if so, could provide any further information into what might be causing it.

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Error casting an object of type java.lang.String cannot be cast to coldfusion.sql.QueryTable to an incompatible type. This usually indicates a programming error in Java, although it could also mean you have tried to use a foreign object in a different way than it was designed.
java.lang.String cannot be cast to coldfusion.sql.QueryTable
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Now, It would be virtually impossible for me to describe my exact template setups here without us all getting very confused. I believe I have narrowed it down though to a query of queries on a query object being passed to this CFC. I have just never seen this error before and cannot find anything over the Internet or these forums.

Any assistance would be great.

Many thanks,
Michael.