iMac screen edge

Never seen or hear or heard of this. Lets start by doing the following:

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.

To be honest, your report indicates the system is kind of mess due to what has been installed.

I see some issues in your report. First is you have Sophos, Antivirus One & VPN Proxy One installed all are considered malware by most experienced users on these forums. Mac OS is catlike in that it cleans itself, Mac OS does not benefit from nor does it require any of the following types of third party apps:

·      Antivirus Apps

·      Cleaning Apps

·      Security Apps

·      VPN Apps

·      Maintenance Apps

What these types of apps do is the exact opposite of what users want. They make Mac OS slow, appear buggy, can damage Mac OS and sometimes create unwanted behaviors like what you are experiencing! In short, they are really bad news!

So the first order of business for your computer is that you need to locate the developers. uninstall instructions for Sophos, Antivirus One & VPN Proxy One and please uninstall each. Because these apps are pretty nasty stuff they tend to leave parts behind after being uninstalled, a testimony to how poorly written they are! To fully ensure you have uninstalled all please download the free version of FindAnyFile directly from the developer. Then have it search your system for all of the following:

• Sophos
• Antivirus One
• VPN Proxy One

Have it Trash any files with those names in them and then ensure the Trash is empty. 

Next, when you installed these one of them (or maybe multiple ones) turned off Apple's Security which means your computer is not secure!!!!!!!!!!. How you fix that is:

1. Click on the Apple Logo at the far left of your Mac's Menu bar.
2. Click on Restart.
3. During Restart Hold down CMD + R during reboot to enter Recovery Mode, make sure the wireless keyboard is plugged into the back of the Mac.
4. Click on the Utilities Menu and launch Terminal.
5. Type in csrutil enable .
6. Restart your Mac again.

Good luck!!