Sounds like some sort of system specific audio driver conflict. Have you checked to make sure your audio card drivers are the most up to date? Have you considered moving to Windows 7 which is massively more secure and better performing? I use a Mac but even I would try to move off Vista as quickly as I could knowing all the issues with Vista. I think it would be worth your trouble just upgrading to Windows 7. I'm not being critical so please don't take it that way but it's well known that Vista was pretty problematic from the start in so many ways that many people quickly upgraded to Win7 or waited and stayed on XP because of the Vista problems.
If you cannot move to Win7 then as a troubleshooting measure try another PC and see if you have the issue there. Another option would be to try using VMWare and load up another OS like XP and see if you get the same issue. It's really a matter of isolating the problem on this PC.
Thank you so much for this reply. I appreciate the advice. I have a new sound card in the computer but will see if there might be a conflict or new drivers to download. Great idea! I do not want to move to Windows 7 in mid semester but will consider it later. I am going to install the newest version on my 32 bit laptop (also on Vista) and see what happens. FYI, I really have not had any issues with Vista but I know others who have.
Again, thank you for your advice. I will see if it works.
Agree with your strategy...I would not do an update to an OS at a critical time. I dothink the audio driver is messed up. When Presenter iis calling the audio driver thru the OS it's running into an issue with the OS.