Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Macs And Viruses
The one reason of Mac operating systems being so popular is that they are considered as less reluctant to virus attacks. But there are questions as to whether really Mac system is virus free? the answer to this question mainly depends on the perception of the definition of what a virus can be. a very basic essence can be that any of the system can get itself infected by a virus attack. When you open an e-mail attachment which contains a virus, it is probable that the entire system crashes down. It will spread the virus over the entire system which might also result in data corruption. However, there is also another property of a virus that it tends to spread on to other systems as well. So, when one considers this definition of a virus, then it is obvious that Mac systems are completely virus protected.
Mac systems to be virus definitions reluctant hold several reasons within it. the first thing is that Mac systems requires its users to setup an administrator account which is responsible for managing all the system files, and the remaining guest accounts are for the personal usage aspects. So, when a virus definition attempts to access the program files of the Mac operating system or tries to make any sort of changes within it, the administrator passcode is required to enter into the system. The main point is that without this password, the user hacker or the attacker cannot provide any harm to the system or to the system files. But, a major issue here is that it can always provide harm to your personal data which is saved on other user accounts. It is not necessary that all the data can be accessed from the administrator account which makes it more receptive to corrupted scripts once the files are executed. In general terms, the security of the system does not lie on high risk.
Secondly, there is a property of viruses that it tends to spread from one operating system to another. This transferring process is supported by the network ports of systems findings those ports which are left open through which the virus can enter from one computer to the other one. The security aspects in Mac operating systems are that the firewall settings are of very high standard and not only the network ports are properly concealed but are much subjected to open. This is the main reason as to why it becomes very difficult for viruses to enter Mac systems and transfer from one to another. As a matter of fact, the settings of the firewall are so high that and the ports are so excellently concealed that even if the network ports gets to open at times, the viruses are still unable to transfer themselves from one system to another. the most interesting part of the entire story is when the virus authors or hackers makes use of the technique of what is called “buffer overflow attack”, in which the attacker sends lot more than malware and viruses to the operating system and under such strong conditions too, Mac OS X withholds its security and does not let the virus definition penetrate into the system.
the launching of the latest Macintosh operating system, Mac OS X 10.7 Lion, has been claimed by its creator company, Apple Inc. as an even more complex operating system because the security settings in this OS is very much enhanced as compared to its predecessors which provides it an additional benefit of being secure from all sorts of virus attack and malware definitions.
In order to deal with these harmful attacks, the Apple Inc. has also released an anti-virus application for Mac operating systems, so that if one does get infected, the cure must be made before the damage has been done. There are several third party applications as well which too are specially designed to fight with viruses in Mac systems and does not provide them room to deeply penetrate within the functioning of the operating system.
concluding, it can be said that Mac are vulnerable to virus attacks, but the stability aspect of the computer system is quite in safe hands and the most important thing is that it does not spread out from one system to another.