DavGio Said:
"Restart loop on 2011 IMac: My 2011 IMac is experiencing a restart loop. After trying many times to enter safe mode the process of holding down all suggested keys and restarting put the computer into single user mode. Where do I go from here to search out and resolve the problem?"
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Trojan (Looping Item):
That would seem to me to be a looping item - a trojan of sorts that keeps repeating itself. So, you may have downloaded or installed software that is not intend for use on your Mac.
So...
First, clear your Temporary Internet Files - Apple Communities
Then, Scan your Mac for Malware:
Use MalwareBytes for Mac --- This is software that searches for malware/adware. So, scan with it and then remove what is found. Once removed, uninstall MalwareBytes for Mac. Then restart the Mac.
Downloads:
- Malwarebytes Anti-Malware for Mac
- Malwarebytes Uninstaller
If Neither Works...
Reinstall the macOS:
1. First, Back up your Mac:
Create a Time Machine backup of your Mac, so that you can have something to restore your Mac from, should anything go wrong with the transfer.
2. Then, Reinstall the macOS:
Nothing would be deleted. It's just that items that have become corrupted or deleted, would be replaced or reinstalled back to where they should be. Go Here: How to reinstall macOS from macOS Recovery - Apple Support