You might either be ignored or get a blast from Joe. He gets asked this question a lot.and if he doesn't answer you might browse through the microHAM user group files. I can't word it as nice as he does, but essentially it is not a microHAM problem. The flashing LED happens when another windows application has control of the sound card. Besides the ones you can see on the devices part of Windows there are sometimes hidden ones too and they sometimes cause problems. He has described the procedure to correct that several times. I don't remember the details, but they are in the past history files of the user group. If I remember correctly the best solution is to uninstall and then reinstall the microHAM router program.
Kevan
N4XL