Acer Aspire 6930 sound problem, and pos...

I have ''Vista Home Basic 64-bit''

Every so often, when watching videos in any player, I suddenly have to go and un-mute my sound. This happens every second or third hour I'm using my computer. Is there anyway to stop it from muting?

Every so often, when I start my computer, I simply get a black screen, I then have to shut down my computer, and restart it. Once started up, I says my computer has recovered from an error, and in ''More Details'' It says ''bluescreen''. I haven't lost any data, however my icons reset themselves, and its really annoying when I only want my computer for a minute... Any help?