I have solved a long-term annoyance with Workstation running on Win 7, 64bit. I reported previously to VMware, but was never resolved. When starting certain conference software in a windows guest, the guest audio is killed for as long as the VM is running (even though the conference stops). As soon as the conference software starts, the guest VM log popup shows the message: "Error creating sound stream". I have had the same problem in Workstation 7.x and 8.x, several MBs, and XP/Win 7 64 bit guests.
The solution was simply to define an audio input device for the host audio device. I think the root cause is that my MBs all come with Realtec "jack detection." So, if you don't have a microphone plugged in, there is no input source defined. I found I could solve the guest VM problem by putting a dummy plug into the microphone jack. This causes the Realtec driver to configure the input source.
I think this is a bug in Workstation since the conference software works fine when run directly on the host. For a few years I assumed it might be a defect of the Realtec implementation on ASUS MBs. This is because I could use an old SoundBlaster IDE card successfully. I think the only reason SoundBlaster worked was because it permanently defined an audio input (did not use "jack detection").