There are random audio advertisements playing in the background on my computer. They are usually short bursts of different ads that come on for about 5 seconds and then turn off for a little while. They are not the result of an application or program, because even when everything is closed I can still hear them. They are fairly recent, and have been playing for about 3 weeks. I can't seem to figure out how to get rid of them. I am running a Windows Vista 32-bit system on a Toshiba laptop. Any help would be greatly appreciated.