According to the company, the feature was originally intended to "allow users to opt-in to adding a useful extension to Chrome as a part of the installation of another application", but has been founded to be abused by third party software developers.
Google said that extensions have been distributed and installed without "proper acknowledgment from users", which was made possible via the Windows registry mechanism for extension deployment.
Chrome 25 will automatically disable all extensions that were installed via the company's external extension deployment options. However, Chrome will show a "one-time prompt to allow the re-enabling of any of the extensions".
Chrome 25 is not expected to be released as a stable version until the end of February.
If it displays ads on one computer and not on the other then yeah, it`s probably hijacked.