I tried simplifying the code somewhat by just doing the DFT, then zeroing out the DC component and then doing the InvDFT. I still got the same result (twothreads running in parallel give the wrong answer, while two threads running serially give the correct answer). In this simple case, the only IPP functions I use are as follows:
Please let me know what other information I can provide that might help in diagnosing this.
Thanks for your help!