Question: error in sqrfree

Hi

In a particular calculation I kepp getting (erratically) the error message,

Error, (in sqrfree) argument must be a polynomial or a rational function in lam

I don't call sqrfree myself, and I don't have anything called lam - so it must be internal to some other call.

When I say it is erratic, sometimes the calculation (which is mostly numerical) continues fine, and sometimes gives this error.

An outline of what I am doing:

First, set up some algebraic/trigonometric equations depending on 2 parameters.  For special values of the parameters I can solve them analytically, but for most values I need to do it numerically, so I have a double loop varying the two parameters.  Both parameters vary from 0 to Pi in steps of 0.01 - so it's a long calculation, with resutls recorded in a table.  The calulations involve first substituting the paramter values (real numbers) and then finding the eigenvalues of several resulting matrices (with real entries) - no algebra that I can see!

After a while the loops exit with this error message - but it's at different points each time, and each time it exits, I go back and repeat the last outer loop and it proceeds fine - for a while!

Any suggestions? (I can send the code, but it's a bit long)

Thanks, James

ps I'm running Maple 13 on a Linux machine