I purchased an Acer AL2423W last October 2006. The image is sweet. The built in speakers are nothing to brag about -- downright stingy -- but they produce some sound. The pivot capability is great, but I don't use it. I got the monitor to use as an extended desktop for a Dell D600 notebook. Connecting via the VGA monitor cable worked fine, but the image didn't always synchronize properly. I had to toggle the dual screen function button on the Dell a few times to get the image to synch. Then it would be good until the next reboot. I don't know if the problem was with the monitor or with the Dell's graphics card or the graphics driver.
In February, I started using a port replicator (docking station) with DVI and VGA outputs. I used the DVI output and that seemed to take care of the synchronizing issue. However, if the computer would hibernate, or the monitors would be set to go to sleep, the ACER monitor would not always awaken, or would turn on for a few seconds and then go dark. If I would turn off the power to the monitor for 15 -30 minutes, then turn it on again, the monitor would work fine. Turning it off for only 5 minutes would not do the trick. I contacted ACER about this. The technicians had no clue and told me to ship the monitor to the repair facility in Texas at my own expense. It comes with a 3-yr warranty that cover repairs and return shipment, but I would have to pay the $35 or so for the initial shipment. I didn't want to be without the monitor, so I have not yet shipped it. Besides, it works great most of the time.
I am now using a Dell D820 with the port replicator. I have been using the DVI connection to the monitor with excellent image results since April 2007. However, the problem with awakening the sleeping monitor continues. I do not know if the problem is due to the monitor or to the port replicator. Since the problem occurred with both my old computer and my new one, I don't think that the computer is the problem. It may be the docking station or the DVI cable.
Yesterday, the monitor started turning the image on and off, or showing the "no signal" indicator superimposed on the still-functioning desktop images. I'm not certain about why this is happening. I disconnected the DVI cable and connected the VGA cable. That seems to have stopped the on/of toggling problem. I was looking for clues about this when I saw your posting.
I need to use the VGA connection for a while to see if that really resolves the matter. The problem may be with the DVI port or cable, but I am still not certain. I can also try a direct VGA connection to the computer, but cannot do a direct DVI connection (computer has no DVI connector-- only the docking station has one.
Another thing about the monitor is that if you are in a very quiet room, you can hear the fluorescent hum of the LCD background light. It sounds like 120Hz -- not too loud but noticeable. I checked several other ACER monitors -- they all sound basically alike, with some slightly louder than others but all quieter than a whisper.
Except for the flaky on/off thing, I really like this monitor to the extent that I bought an ACER X241W for my wife. It is virtually the same monitor without the built-in speakers (which are not great anyway) and without the swiveling and height-adjustable stand. It also does not pivot, but the image may be pivotable if you use other graphics software and buy a different mounting system, such as an articulating arm. I paid nearly $800 (then got a $100 rebate) for the AL2423W last fall, and $399 (and expect a $100 rebate) for the X241W two months ago, both from Micro Center. We have not noticed trouble with the X241W. It is connected, via DVI cable to an HP Pavilion a420n desktop computer with a Radeon 9550 AGP graphics card.
I got the Acer X241W from MicroCenter for the same price. I was really surprised at how light-weight it was/is. I was getting the same no signal screen over my computer display...weird. I figured it out and have not had the issue again. I changed power outlets from one battery backup to another. I tried several and apparently it is some power draw issue. My understanding is your issue was with a different Acer model. Good luck with yours.