Hi -- I've thought of 10 things that could be your problem ...
1) Could be a faulty connection somewhere. Probably where the speakers plug into the computer
2) Could be a static electricity build up .. is your computer grounded properly?
3) Could be a windows sound that you have assigned to a certain action such as minimising windows, that you do once every 5 minutes odd.
4) Could actually be a sound coming from a fly-killing light you have in the room
5) You could have messenger, or yahoo chat running in the background. Someone else on the internet is in the same room as you, and once every five minutes they are making the 'bzzzzzzz .. slap' sound into their microphone for some bizarre reason.
6) You could be playing a CD that is completely empty, apart from having the sound recorded on it once every 5 minutes.
7) You could have installed a game .. gone into the 'Sound FX' directory and copied over one of the sounds with a .wav of 'bzzzz .. SLAP'. Therefore every time you launch a hand-held nuke against the enemy (about once every five minutes) -- this sound occurs.
You could have assigned a specific sound to your anti-virus or firewall program. You are being attacked once every 5 minutes .. this sound is warning you of the fact.
9) There could be a fly or bee stuck inside your speaker. Every 5 minutes he gets the strength to try and escape .. but just slaps into the plastic box.
10) You could be listening to internet radio. A particularly bizarre Norwegian Goat-herding channel .. in which the only sounds they really like to listen to -- about once every 5 minutes .. is 'bzzzzzzzz .. SLAP'.
Glad to be of assistance.
Can anyone save me from my killing spree? Need some kinda computer techie/nerd/expert etc.
Great replies!! (and some sensible ones too! - I had an ad swatter that made a similar noise whenever it stopped a popup - it could be that???)