A quick scan seems to work fine.
But a full scan fails with a system shutdown. Could be malware, especially with all those Thunderbird problems.
Try booting into Safe Mode with Networking, update McAfee fro there, and then run a full scan in Safe Mode. It may work better there.
Edit - That username needs to be changed. We can't allow email addresses as usernames, for your own security. That way lies spam forever.
I was just about to mention that fact, after seeing it
Your user name has been changed to ed (just that) so you will need to log out and then back in again using ed as the user name.
Those hundreds of email rejection could indicate a real infection at your end or at a friend's who has your email in his/her address book and the infection is spoofing you as the sender. These are quite common and are also quite difficult to pin down.
I recommend the Safe Mode w/Networking suggestion - but note that to run McAfee in that mode you would need to go into My Computer/Computer (depending on your system) and right-click the drive and select Scan. The SecurityCenter can';t be opened in that mode.
I also recommend using some extra tools, some are mentioned in the last link in my signature below.
NOTE: Malwarebytes Free can not only be download and installed in Safe Mode with Networking, but it can also be updated and run in that mode.
Then make sure your system is totally up to date, including any bits you may not use, IE for instance. Very important. Then be very careful what you download and where it's from and never, ever publish personal information in public (email addresses, phone numbers etc.).
Thanks to all who have repied. After doing what you have recommended in safe mode, the problem continues.
This could, I suppose, be hardware-related. Your hard drive may be either producing file-read errors or actually in the process of failing.
What operating system is this?
Adding to Hayton's advice I would suggest you Turn Off Access Protection and push a Manual Update.
Open McAfee UI > Navigation > General Settings and Alerts > Access Protection > Uncheck and click Apply.
Wait for the update to complete and Restart machine if required.
and reenable access protection...