I have MacBook Air, 13 inches, macOS Sierra. Version 10.12.5

Sometimes when I put mouse over or click on some text - the area where mouse pointing getting red, sometimes this red area is getting bigger and started blinking and looks like those changings on screen are nor related to mouse.

It happened once a week and I could not tell what trigger this. I was told by Mac representative that this is probably some sort of malware.

But I have application Adware Medic and it doesn't detect any malware.

I think that it is possible hardware issue.

Any suggestion what cause this issue and how to fix it?


//EDITED Sometimes I have no red (see pictures below):

no red in field

no red but green in field

  • You should try Malwarebytes as well as Adware Medic. – IconDaemon Sep 9 '17 at 1:38
  • Could I use Malwarebytes a free version? – User Sep 9 '17 at 15:27

You may be able to run some diagnostic tests yourself if you follow the Apple article How to use Apple Diagnostics which also includes a link for machines introduced before 2013.

Worst case scenario: you have a graphics card issue. The in-built diagnostic tests may not be able to give a definite answer. An Apple Store or authorised repairer can diagnose this.

Before assuming the worst, I would recommend backing up your machine, running some diagnostic tests, and if you find no problems try re-installing the operating system. It is possible that re-installing your non-Apple applications one-by-one may reveal the culprit.

  • What do you mean by non-Apple applications? – User Sep 9 '17 at 15:29
  • The 'free' version is a trial version, but it installs files you need to later remove. – IconDaemon Sep 9 '17 at 19:04
  • Re: @User's comment: By "non-Apple applications", I meant ones like Photoshop, Malwarebytes, and all the other applications which aren't from Apple or the Apple App Store. If it is NOT a hardware issue, my first step would be to (1) backup with TimeMachine (2) reinstall macOS (3) if the problem still occurs then wipe the disk, reinstall macOS and all the Applications and settings from TimeMachine, (4) if issues still happen then wipe again and install the applications one by one, starting with Apple s/w, then AppStore apps, then others, until you find which one is causing the problem. – Mic Channel Sep 10 '17 at 15:41
  • I still have guarantee on this Mac. Should I exercise this guarantee telling what is the issue and let the store to fix it or should i proceed to do it myself. I have back up but I've never done the next steps like reinstall OS... Is it complicated and/or time consuming? – User Sep 10 '17 at 16:00
  • Yes, If your machine is still under guarantee, then do exercise your rights and let the store fix it. Re-installing software is quite straightforward but can be fairly time-consuming (taking hours or possibly longer). If you want to look yourself before taking it to the store, try the Apple Diagnostic software as this only takes a few minutes or less than an hour. Please edit your question or add a comment saying exactly which model of Macbook Air it is. Some old or second-hand models might not have Apple Diagnostic software on them. – Mic Channel Sep 10 '17 at 16:10

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