My screen on my Sony Vaio LV140J started flashing recently at random. It goes black for 1-2 seconds and then resumes as normal. When it flashes I lose sound and everything but it resumes normal afterwords. All Sony could tell me is to update the drivers and I tried that with no luck at all an they can help me no further because they want original purchase receipt for repairs.. a bad part of Sony considering how we can never keep up with those.. It flashes at random sometimes every few minutes and other times every hour or so. It is dual voltage and I tried switching from 220 to 110 and that did not solve the problem either.

This sounds like a power issue. I realy hate thos one in all systems. They are such a pain to get fixed. I would guess that your power supply is going bad, but it's possible that you may have a bug. You need to first test to see if it's a hardware problem or software. To do this, reboot the computer and press either 'F2' or 'delete key' to go into the bios settings. Once you are in the setup menu, let it sit for a while and see if the screen flickers. If it does, then you have something going bad in with your hardware. If it hasn't been cleaned in a while, you can try spraying it down with canned air. Too much dust and dirt can cause heat problems, and heat problems can cause strange issues to happen. If this doesn't work then your power supply is probably going bad and will have to be replaced.

If it doesn't give you any problems when you are in the bios menu, but does when you boot into Windows, then you may have a driver issue. Uninstall the drivers, download the latest ones, and reinstall. A great way to tell if it's a driver issue, is to boot into safe mode. If you don't have any issues in safe mode, but you do when otherwise, then it's a good assumption that you have a bad driver causing the problem.

Let me know if any of this helps, or if it doesn't.