Computer got Safari hijacked by the "police" virus. Temporary solved by using Firefox instead. Questions:
Read on numerous forums that you could reinstall OS X by holding down cmd + R keys. However, this computer ignores this.
Also tried the CD/DVD which came with the computer. Clicking on Install OS X renders something like You cannot install this version.
Also tried starting with the CD/DVD by holding down the C key but that makes the screen go all gray and stay such.