This depends on a lot of factors including your computer usage, sites visited, email activity, etc. A rule of thumb is that if your antivirus software has an automatic scan feature that you can set a specific time for, is that you should set it for every night while you are offline and the computer can scan uninhibited. On the same note however, if you are not an active user, and do not engage in what we at Smiley Face PC like to call ROB or Risky Online Behavior, then you may get away with a less frequent scan. Risky Online Behavior is where you are visiting websites that are known to attach a great deal of cookies, or opening forwarded emails that are more apt to carry a virus, and using file sharing programs that carry all manner of malware. While most users will engage in some degree of ROB in using their computers, usage of the right firewalls and screening practices will prevent most intrusions by malware. Smiley Face PC will best determine the need for your virus scans after consultation with you. We can best determine what level of protection you need and set the virus protection and scans accordingly. Then for your peace of mind, technical support at Smiley Face PC is a moment behind in case the virus scan did pick up something.