Abstract: A method, system, and computer-readable medium are described for assisting in protecting computing systems from unauthorized programs, such as by preventing computer viruses and other types of malware programs from executing during startup of a computing system and/or at other times. In some situations, computing system protection is provided by executing programs only if they have been confirmed as being authorized, which may be determined in various ways (e.g., if a program is automatically determined to be unchanged since a prior time when the program was authorized or to match a set of programs identified as being allowable, or if an appropriate user provides appropriate information). This abstract is provided to comply with rules requiring an abstract, and it is submitted with the intention that it will not be used to interpret or limit the scope or meaning of the claims.