Do I have a virus or Trojan malware on my MacBook Pro?

Question

I downloaded a faulty mp3 file from the internet which I think infected my computer with either a virus or Trojan malware. It took over my computer and disallowed me from accessing any applications. I clicked on Finder, for example, and a window would pop up saying, "Application not found," with a number after it. I rebooted by computer and was able to log back in using Safe Mode. Here, I deleted the  file I had downloaded, or so I thought, by dragging it to the trash and emptying it. However, my computer is acting bizarre and barely functions. I am unable to use DVD Player, it says, "There was an initialization error" with code -70017. My volume is unaccessible, there is a circle with a slash through it when I try to use it. Itunes will not work, Iphoto keeps crashing and will not open, and my internet browser is extremely slow and will not play video.
I have downloaded and installed Sophoes Anti-Virus and MacScan in an attempt to rid my computer of the virus but it did not seem to do anything.
Suggestions as to how to fix this problem would be greatly appreciated.

Answer 1

This is not the work of a virus, or any other kind of malware. What it sounds like is a very badly corrupt hard drive causing all manner of corruption in your various system components and applications. You probably need to erase your hard drive and reinstall the system from scratch, as ds store has said.
If you actually had malware, Sophos would find it. If Sophos found nothing, there was almost certainly nothing to find. If something like Sophos ever should find malware, unless the malware has "OSX" or "MacOS" in the name, it probably isn't Mac malware and thus isn't something you need to worry about (other than not passing it on to other people).
MacScan is junk. It serves no useful purpose. See:
MacScan disappoints