There are viruses and trojans which can do all kinds of audio hijinks.
Have your office computers scanned with an antivirus program first and see if it stops.
If that doesn't work, your best bet would be to go to our HijackThis Forum and post a log from one of the infected computers. /f67-Trend_Micro_HijackThis_Logs.html
_________________
_________________ Microsoft MVP Consumer Security 2006, 2007 & 2008
You can post new topics in this forum You can reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You can download files in this forum