I bought my granddaughter a Dell Inspiron 15 (3520) in October 2012.  I believe she has Windows 7 on it.  She said she is getting thick lines across the screen intermitantly.  She described them as like the old tv test pattern.  She thinks it happens when she is using the touch mouse pad.  It is no longer in warranty so looking for some things to try before I contact Dell.  She is in full panic she has all of her college applications on it. 
Thanks for the help!!!
lyn
Don't know about Dell, but I've come across PLENTY of Acer laptops that develop this or similar problems. In every case it was basically the result of using the laptop as a desktop PC - that is, always running on the AC power.

Most laptops constantly charge, thereby overcharging the battery if you leave it fitted all the time. This causes the battery to eventually fail due to overheating. It may still work when the AC is unplugged, but won't hold it's charge anywhere near as long as it should. The first signs of this is that the battery will be a lot warmer than it should be after running on the AC power for a while. Eventually, the cooked battery starts causing fluctuations in the power supply, which can lead to lines on the screen, rebooting out of the blue, network dropouts, screen flickering, color loss - just about any intermittent problem you can think of. There's all types of symptoms.

The easy way to test and if this is the problem, and if so fix it - is to remove the battery and run off the AC without the battery fitted. See how this GOES over a few days, and if it solves the problem then replace the battery. You shouldn't use the old one again because it will definately be damaged.

With laptops, you should avoid leaving the battery in when running mostly of the AC. In regard to the battery itself, the user manual should have some information on how best to prolong it's life. If it doesn't, I can tell you that a few years ago I was researching cordless power tools, and many places advise that those batteries should be stored at around half charge when not used for any longer than two weeks or so. Some IT web sites advise that this is good practice for laptop batteries as well.

Basically, whenever you experience an intermittent problem with a laptop, try removing the battery and running on AC before doing anything else. You'd be surprised how often the problem is a cooked battery.Thank you so much!!  SURE hope it works.  She has taken great care of her laptop and feels just awful along with major panic.
lynNo problem. Let us know how you get on.So I ordered the battery.  While she was waiting I had her pull the battery and use the power CORD.  It worked fine so I believe the battery is the problem. 

The battery has arrived.   It is not a Dell battery.  The laptop is not recognizing the battery.  Not sure what to do next.

Thanks!!
lyn