Try this to find it.
[Ctrl] + [F] (this brings up the browser search function, works in a huge number of programs in Windows and is an amazing tool that many people don't use)
Type "Advanced Search" (This should highlight the link to the forum's powerful search page)
Click the link and adjust the parameters for searching to meet your needs. Unfortunately this returns links to the topics a search turned up and not the individual posts (A pain when the topic has 30 pages of replies), but then you can use the control F function to search within the topic.