I believe he means the Operating System.
Yup - sorry if I didn't clarify sufficiently :-/ Now obviously this would be on a machine you could do without for a day or two, but would provide the most bullet-proof method of identify exactly when and where your search behaviour is being hijacked... would also prove once and for all as to whether is a plugin, application or your ISP which is responsible (if ISP should be present either immediately or shortly after first connection to internet, but seeing as has not happened to ALL machines at same point, am really not convinced this is the source).
The beauty of this is that it not only alert you as to what software NOT to install from here on in, but advises everyone else :)