Have you notice the newest feature of Google Webmaster tools? If not then you need to view the latest inclusion “Linked From”. This will enable a webmaster to point out the page where the wrong URL is placed without making an extensive search. Previously, Webmasters could only get the report of “not found” errors but they were not in the position to locate the origin of the problem or to fix the problem. Therefore, the errors remained unchanged and the source of the errors went undetected. However, thanks to this addiction in Google Webmaster Tools, now webmasters can find out the source of the “404 pages” or “Not Found” urls easily. Besides that, this feature is giving them an opportunity to rectify these problems without wasting a long time. One just has to click on the link “Linked From” for locating the origin of the error and then work accordingly.

(Image Source : Google.com)