A method and apparatus for scanning for or removing malware from a computer device. Under normal circumstances, the computer device is controlled by a first operating system installed in a memory of the device. In order to scan for or remove the malware from the computer device, control of the computer device is passed from the first operating system to a second operating system and, under the control of the second operating system, the device is either scanned for malware or the malware is removed. This allows malware to be detected or removed, even if it has affected the first operating system in some way in order to evade detection or removal.