DRM removal software for the Mac is a bit thin on the ground compared to the PC, but AppleMacsoft DRM converter comes to the rescue; incidentally, there is also a Windows version. The software uses a virtual CD writer (same method as Noteburner 2) in conjunction with the iTunes software to legally produce a DRM-free copy of the original.
The Best Free Anti-Spyware app downloads for Mac: Malwarebytes Anti-Malware Little Snitch MacScan Boonana Trojan Horse Removal Tool DNSChanger Removal.

That’s why special tools are required to remove Mac malware and other unwanted apps. Why is TunesBro CleanGeeker the Best Malware Removal for Mac? Removing malware and other unwanted programs from your Mac often requires root access, which poses the danger of altering system files and disabling your computer altogether. However, automatic update is not available. If you wish your program to stay up to date, you may check on the App Store to manually update iAntiVirus. McAfee Virus Scan. This security protection and malware removal Mac program is a powerful tool for keeping your computer free.

99.99% of malware is completely hidden from sight. Malware authors aren't interested in having their exploits detected by suspicious users. While malware can't be entirely ruled out in your case, you are probably experiencing some kind of software or hardware problem (maybe the GPU.)

Using a constantly on AV program runs the risk of slowing down your Mac, or creating other issues. In addition, no AV program can identify an infection that hasn't yet been catalogued, and most AV programs use heuristics--in plain talk they are making educated guesses, which often lead to false positives. You may still want to run some kind of AV. The best bet out there is probably Sophos, or VirusBarrier Express (scans only manually and makes no system modifications. MacKeeper is total garbage. Although it does now use a respectable AV program, Avira, you could run that without buying the whole package.

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ClamXav is a decent program run by a developer with considerable integrity, but it has fallen way behind in its detection rate. And MacScan is pathetic at identifying malware. But is the best at finding known keyloggers. And as far as I know, most if not all of those will have needed to be installed with physical access to the Mac.

Mac App Remover Review

Best App Removal Tool For Mac

Here's a good read on this subject.

App Remover Mac

Mac App Remover Review

Best App Removal Tool For Mac

License Removal Tool For Mac