Vertical lines and redundant sound

I am having problems with vertical lines or colors popping
up and blocking out the whole screen, only way to stop it,
is to reboot manually. Sometimes this happens 8 times in 3
hours time. I also am having problems with redundant sound
loop, does not go away with a reboot. Please help, I have
taken this computer into the shop twice now, the problems
did not show up at the shop. I even switched monitors, but
that did not help.