Hello Ronzie, Took drastic action and un-installed all FSX etc. Re-installed on other hard disk. Switched McAfee off and installed radar Contact, tested voice and all was well. McAfee back on and still tested OK. Have just tried a basic trip and all is still working. We seem to have got it, I wonder if all now being on second hard disk away from windows did the trick. Thanks for your help and fingers crossed all will continue OK