horizantial lines/waves from bottom to top on lcd monitor

[multi-tasking_guy]

i have a LG Flatron W2242TQ that has horizontal waves/lines from the bottom to top of the monitor

what exactly is causing this? another of my monitors is doing this also,

video below

 

[multi-tasking_guy]

update! i plugged the monitor into a different outlet and it doesn't happen

so its the electric outlet that is causing this, what exactly does this mean