viewsonic g90fb screen image keeps moving

hi guys. i've got a viewsonic g90fb monitor. i've been
having a strange problem these days. i work hard to adjust
the on-screen image position and a few hours later, i
find that the on-screen image has moved. it happens quite
often and i am sure it is not one of my friends playing a
prank. i've got a few things around my monitor, like a
printer, keyboard, webcam, racing wheel, cordless gamepad,
shielded speakers, vcr, a bunch of cds and a box of
pushpins. i can't figure out which of these could be
causing this. i also had moire patterns on my monitor but
i adjusted the monitor settings and it has been fine since.

can anyone help me with this? i spent a couple of hundred
bucks on the monitor and i want it to be perfect.
tia.
-satprem

Bus station is where buses stop
Train station is where trains stop
On my desk I have a work station...