(XP Home Edition) I made a mess trying to change security from Zone Alarm to Comodo - ended up with Avast. The changes ( the initial try of Comodo) triggered a 10 second intermittent 'siren' from inside the unit (standard - not laptop). I've tried every kind of removal, reinstall, reboot combination - and the 'siren' remains - even coming with internet completely removed. The siren does NOT come through amp and speakers connected via sound card. But when go to Device Manager etc. to disable sound the output from sound card also shuts off. Volume controls don't affect the 'siren' but do affect the sound card. Everything else is working and I expect I'll have to do something 'serious' at some point - the unit is due for a change sometime in the near future. But is there something I can do to shut off thiis infernal siren in the meantime - while still being able to use the sound card output? Thanks.