'clicking' noise from acer laptop speakers

Hi,

Just out of the blue our Acer aspire 5715z laptop has started to make a repetative 'clicking noise from the speakers, and we can't work out why.
The volume control bar appears to be going up and down constantly, and adjusting the volume or muting does nothing. No other sounds can be heard either (i.e. music/video)

We have run AVG antivirus and no sign of anything

We have called acer technical support as it is under warranty, and they suggested a system restore, which we have now completed, but the clicking is still there. we called back and they have now told us that although under warranty, if the fault turns out to be a software related fault then we have to pay for the repair which we don't want to do as its not our fault.:mad:

How can we ensure that its not a software related fault? IS there anything else we can try?

many thanks :confused:

To totally eliminate software as the cause, I would burn Knoppix to CD (http://www.knoppix.org/) and load the Knoppix operating system up via CD-ROM. If you get the clicking noise in Knoppix, then it's most definitely a hardware issue.

TEk