System restore

"Sir, that computer in the office has a problem. The 'AVG' and 'Microsoft security essentials' antivirus software installed on it has been inactivated automatically. I cannot get either of them to do antivirus scanning. The is a new security software that pops up periodically and says there are some viruses which it won't remove unless we buy that software." our professor in charge of the computers in the department said. "It is a malware. Somehow it tempted someone sitting on that computer to install it. It has maliciously inactivated our two licensed programs" I said. "If you uninstall and reinstall them, this will inactivate them again." "I tried to uninstall them. The computer said the system administrator has stopped me access to do that. But I was logged in as administrator." "The malware makes changes that makes the system believe what it said to you" I smiled. "So I will have to format C and install Windows XP again." "No. There is an easier way. Restore the system to the earliest date possible. Then this problem will go away" I said. Two days passed. Finally the professor got time out of her clinical and administrative work when some other pressing work was not being done on that computer by other people. "Sir, the system is restored. The problem is solved." I was happy. The system engineers of the institute would have been happy too if they had known we had saved them a visit and some work. The other computer users in the institute would have been happy too because we had kept the engineers available for them instead of keeping them on our system. I will be further happy if any of my reader or a new reader who reaches this page by 'Google' search and finds this information useful.