You have some major issues. First is Apple's security has been diasabled, this is critical and needs to be addressed. You will need to contact AppleCare for assistance on that. Next there is no backup of this computer. At the VERY least Time Machine should be running. Operating ANY computer without a full backup is shortsighted and a guarantee you will lose data. Please refer to Back up your Mac with Time Machine - Apple Support and purchase yourself a high quality EHD such as a OWC Mercury Elite Pro!
Finally please read and follow the critical information below!
The best antivirus, cleaning app, and overall maintenance app for Mac OS is Mac OS itself. All you need to do with Mac OS to keep it secure and running well is to keep it up-to-date and do periodic (about 1x per week) restarts. Other than that, leave it alone. Adding third party antivirus, cleaning, security and other types of maintenance apps to Mac OS adds no additional level of security. The only thing these apps do is have the opposite affect users want. They make Mac OS slow, unstable, generate odd behavior (much like you are experiencing) and make Mac OS appear buggy.
Please locate the developers uninstall instructions for Sophos and follow to the letter. Then restart in Safe Mode per the directions in Use safe mode to isolate issues with your Mac and then restart normally.