Area 51 Servers

When I play hl,my pc sound often goes off or it makes weird noise like the speaker is broken.
Restarting my pc fixes it. (This is not my pc or setting problem)
Josh said it happens for him too and so as few other people.
I'm guessing it has something to do with most likely hl's update but is there any fix ?
If there is,I'd like to know.
Thanks :3

i've experienced similar thing on skype and teamspeak. the sound was still there, but it sounded broken and metalic and stuff so i restarted pulseaudio and it was ok.