I downloaded the ARMA2 Demo from Steam - the download and installation went through with no visible problems. When I try to run it - it runs and seems to work ok - responds to controls and such, but there is no sound - not a peep. Considering that otherwise the sound works just fine, including other games both steam and non steam, I assume the problem is in the ARMA2 Demo.
My computer runs Vista64 on Intel Quad with 8GB of RAM
Any thoughts?