I ran Smart Scan. Then I ran Deep Scan which is still running 24 hours later and always indicates 95% completed. It's constantly working on my 4TB Time Machine external drive. - I took my iMac and 4TB external drive to computer repair. All viruses and malware were removed. - It's now two weeks later. I ran Smart Scan again. No viruses. Then I ran Deep Scan again. It is still running 24 hours later and always indicates 95% completed. It is once again constantly working on my 4TB Time Machine external drive. - HELP!!