I would try to connect the monitor with another cable and to a different unit to see if that fixes it, it may have gone bad and may be an easier fix than calling in to set it up for service and mailing it in for repair. I'm fairly certain when you call they are going to ask if you tried other cables or connected it to another unit.
Please join me in congratulating IronFly who is the first Acer Community Member to achieve the rank of ACE Pathfinder. IronFly has shown a consistent willingness to help others and has worked hard to earn this new Rank. Congrats and Thank You IronFly.