I hope someone can please help me with a problem I have been experiencing lately with my computer. I sometimes hear random audio ads playing in the background for no reason. It sounds like a commercial ad playing, yet there are no other windows open or programs running, other than the one I am using, which is not playing video or audio. This occurs about once every few days when I am online, and I am only able to stop the background audio, if I restart my computer. The audio is not constant, it just randomly appears out of nowhere on any given day or time. I checked my volume mixer and there was an application named "name not available". When I closed the volume mixer and opened it again, it was gone, and has not reappeared. My Firefox browser is very slow, and constantly freezing and crashing ever since this audio problem began. I am usually very cautious about the websites I visit, so I don't know how I might have become infected. I scanned my system with Norton 360 and Malwarebytes, but both results came back clean, but I am still convinced something is not right. I am running Windows Vista Home Premium 32 - bit operating system Service Pack 2. I am not very computer savvy, so I do not want to do anything without advice first. I am hoping there is someone who can please help me, as I have never experienced having a virus before. Thank you so much for all of your help.