Op? What's the situation now, what all have you tried ... etc? Op? Respond dammit! Op !?!

PS, really do want to maintain that weird thought about checking stuff like a power strip, they do go bad and could cause all manner of odd tech problems. Likely to be the absolute last thing anyone would consider or never even check at all.
Ps2, How insidious would it be if it turned out the cord or port Op is using to connect this problem system to that monitor has a short in it? We could all be standing there with physical access to the damn thing and would probably never get around to checking that.