Hi All- Not sure what's going on here, I've never had this happen before. I'm getting a commercial from "National Car rentals"(very LOUD!) and 1 other I'm not sure what it is(very SOFT) they periodically(several times a day) just break in and blast their message. I never hear it at night when I put the computer to sleep but I think it has woke up the iMac and spewed it's audio during the day. This is really new to me, I've never heard of it before. It will break into a movie your watching, if your streaming radio channels or if your not doing any of that just on the computer..... Any clues how to stop it?