About a week ago my laptop performed an automatic update. All appeared well until I realised that it wasn't making any sound. The volume wasn't muted and could be raised or lowered, but no music, video or system sounds would be heard. Strangely, Youtube videos would not play properly - a video would load for a couple of seconds, then be replaced with the standard "an error occured" screen, which usually indicates a connection issue. Videos on my HDD and on other sites played perfectly, albeit without sound.
Restarting my laptop solved the issue completely, but it's returned twice in the days since then - each time resolved by a restart. Can anybody offer any explanation as to the issue here, and any advice how to fix it? While it doesn't seem to be a critical problem it's extremely inconvenient, and I don't want to have to be restarting my computer on a regular basis.