Try to give the VM one more vCPU to rule out contention in the guest.
Anything in the pcoip-server logs?
We are seeing the same issues with WYSE P20's and View 4.6. We have to cycle the Audio service and reboot the Thin Client. Are machines are dual core Win7 machines with 8GB of RAM - No contention.
As a follow up, removing the WHQL driver and reverting to the default output only one solves the issue, no more audio "disappearances". There must be some bug somewhere. Our Windows 7 VM is also 2 vCPUs and no contention is present.
The latest version of the Teradici PCoIP firmware (PCoIP Firmware 3.3.1) fixes an issue with audio and Windows 7 64-bit. I would recommend updating to that and seeing if it fixes your issue: http://techsupport.teradici.com/ics/support/default.asp?deptID=15164&task=knowledge&questionID=622
- Fixed USB audio issue with VMware View guests running Microsoft Windows 7 64-bit host OS