Monitor Question

I recently puchased a used hp ultra vga 1280
monitor which i am using w/upgraded pc.the graphics card is a pretty cheap Jaton card w/4mb memory.My question is on very frequent occasions i get a slight shimmy, shaky screen,it is a little irritating.anyhow could
it be that i have another monitor in close proximity,does electromagnetic discharge play any?perhaps my power supply is all bunched in on outlet?i just looked to see i have 6 out from a dual wall outlet.lastly i hope IT IS NOT A SIGN TOLOOK FOR ANOTHER MONITOR.THAT WON’T MAKE ME TOO HAPPY–any input will be appreciated &THANKX–AZIZ