[CentOS] centos6 and virtualbox audio problem

hello,

host:  centos6  64bit  (dell desktop)
guest: windows 7 64bit
virtualbox:  4.3.30

problem:  host has audio but guest does not.
i.e. when virtualbox comes up, it says:

No audio devices could  be opened.
ErrorID: HostAudioNotResponding




#lspci -nn | grep -i audio
00:1b.0 Audio device [0403]: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller [8
086:1c20] (rev 04)
01:00.1 Audio device [0403]: NVIDIA Corporation GF119 HDMI Audio Controller [10de:0e08] (rev a1)


Pulse audio and Alsa installed on the host.

trying these settings have not worked so  far
letting me have audio on the guest:

Host Audio Driver: OSS,PULSE,ALSA
Audio Controller: Intel HD

I am not seeing any audio-related errors in virtualbox log.


lot of time spent on this so far; any idea as what to do
next will be greatly appreciated.


thank you,
F-