Strange mex behavior - calling second function corrupts inputs in MatLab?

I am having some very strange mex behavior. I have two mex functions, both of which generate 2 arrays of integer outputs. The outputs from one can be used as the inputs to another. When this is done, the output from the first function (viewed in matlab) becomes corrupted (takes different, non-integer values). Additionally, calling the second function seems to cause matlab to become unstable - closing matlab after running it causes matlab to crash, as does trying to run it twice within one session. No errors are generated, just a crash. All this together makes me suspect some sort of memory issue, but I have no idea what could cause it. Any ideas?

Sketch of what happens:

MxFn1(inputs)
read inputs in with mxGetPr
Get two integer arrays A,B
Convert to double arrays, output with mex

Back in Matlab, at this point A,B read correctly

call MxFn2(inputs, including A,B)
A, B read in correctly (verified with mexprintf)
A,B themselves are not changed, just copied into a new array
MxFn2 runs
MxFn2 creates A'B', converts to double arrays, outputs
A',B' are correct (verified with mexprintf)
output A',B'

A,B,A',B'now ready incorrectly in MatLab
Attempting to run MxFn2 again causes a crash, as does exiting matlab

I use the same input/output methodology in both functions.

[Geoff Hayes]

Ryan - you may have to post the code for each of your two functions. You are probably right in thinking that there is some sort of memory issue within in one or both of the functions. Though I am a little unclear on the following

 call MxFn2(inputs, including A,B)
 A, B read in correctly (verified with mexprintf)
 A,B themselves are not changed, just copied into a new array
 MxFn2 runs

You call MxFn2 and then on the fourth line it runs? Please clarify.

[Ryan Pyle]

I was hoping to avoid posting the actual code - they are both fairly large and complex functions!

What I meant was the the second function receives A,B (outputs from previous function) as inputs. These inputs are read in correctly. The calculation portion of the function then runs, and output A',B' (still within mex function) reads out correctly. A',B' are then returned as outputs to matlab, where they are no longer correct, and somehow the original A,B have been corrupted as well.

[Geoff Hayes]

Ryan - could you show (from the Command Window) how you are calling your functions, checking the input and output, and noting how the A',B' are then returned as outputs to matlab, where they are no longer correct?

[Ryan Pyle]

Found my mistake - I had accidentally called mxFree on Wr, I0r where Wr and I0r where my plhs[0] and plhs[1] in the second function. Thanks for your help!