malware

How does a person determine if their machine has malware or a virus.

Recently there was the security article pertaining to, any one could log into a Apple Macintosh using the word root.

And then there was a article that Apple Macintosh had a fix within 24 hours of the security notice.

I did receive a security update a few days later.

last night when I put the machine to sleep it would come back to full screen mode.

Then when I went to shut it down the behavior was weird and it finally began to go into shut down yet the screen turned completely green before shutting down.

This morning when I turned the machine back on the password box had a question mark in the right hand side of which I have never seen before.

Is the any real accurate information pertaining to any virus malware that is currently infecting Apple Macintosh machines.

Thank you