Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows. I'm sorry that you're having this issue. It would be my pleasure to help you resolve this. Have you by any chance tried shutting your Macbook off since you returned home?
It is quite possible that it will be the easiest fastest way to diagnose. If you don't mind, let me research just a few moments please, and ask a few more questions. Have you checked to make sure that your OS is up-to-date? Have you run any hardware tests? I would tend to think hardware issue, however, that fact that it clears up when you do a screenshot puzzles me a bit. Do the lines actually clear up on the screen or do they just not show up in the screen shot that is saved?
Just got it. Thanks! I have a strong suspicion that this is a hardware problem. I recommend running the Apple Hardware Test. Pleas emake sure tha your Macbook is plugged in before doing this. Let me know if you need help with any of the steps or have any questions.
Using Apple Hardware Test
Note: Your test results will appear in the window in the bottom-right of the console.
I apologize. A client had a follow up question that I thought would only take a moment. The good news fo you is that i DO answer follow up questions. I'm sorry that you had to wait though. Please bookmark this page by pressing CTRL D. Also, you should be receiving an email each time we chat. You can click on a link in any of the emails to return to the question. Thanks so much for your patience.