Acer - Screen Blackouts

I very recently got Acer TravelMate 5520 with Vista, AMD Athalon 64 X2 Dual-Core Processor TK-55 1.80 GHz, and 766 mb of RAM.

Now, the thing is, the screen has blacked out on me twice (sound disappearing as well), and both times, no matter how long I waited, nothing happened, and I had to force it to shut down.
When I start it up again it looks fine, but being a big novice when it comes to this sort of computer stuff, I don't know what I should check for faults.
And I'd rather not let this keep happening.

Help, please?

I have also had this issue with my Acer Extensa 5420 Laptop.
It is running an ATI Xpress 1250. It is on the best buy website right now on sale for 499.
The screen will black out while working/clicking and I am forced to do a hard shutdown (no other possible way to get the display working). The PC is still running but the display is just gone. It doesnt loose power since the backlight is still on so it isn't an issue with the LCD display, probably with the motherboard or ATI graphics. Everything is fine when i start up again but this causes me to lose work and settings. I called best buy and they had not heard of this issue with the Acer laptops. Has happened twice and I just purchased this laptop yesterday.
I disabled hibernation and installed all updates including the optional ones. If this keeps happening I will probably try and get this laptop replaced under warranty. It is most likely a hardware issue.

Yea Mine has done the same thing maybe 3 times now. Today it did it after just shutting the lid on it last night without actually going through the steps of shutting it down. I don't know if this is bad idea or but I have been doing that ever since I purchased it from best buy. I am in california, and still have a few days on my return policy, do you think that I should exchange it for another one? I don't want the frequency of this problem going up. If it does and it's after 30 days I believe that I read somwhere that ACER is not to helpful. What do you guys think?

I haven't had the blackout issue recur since I posted the first time. The only issue I have been having now is choppy performance while watching video, listening to music, etc...This is the low end acer so I am not suprised. Next laptop I get will not be an Acer.

Still having this issue and it is worse now. After around 2 hours of use the screen will black out and I am forced to reboot. This is a hardware issue. I have disk wiped and reinstalled a fresh ver of windows and drivers.
Still happening. I have my pc to shut down when I press the power button and to hibernate when the lid is closed. Neither of these happen when the blackout occurs and I am forced to shut down loosing any unsaved data.I'll be looking into replacing this PC through warranty.