I have a page that i suspect lowered my google ranking.

Does anyone know of a way that I can stop the google trawlers finding it?

You can either use a robots.txt file or nofollow tag to block the search spider’s form referencing a specific page or directory.

If you've not used robots.txt before have a look at robotstxt.org it has all the information you'll need.

I've heard of robots.txt files before but not ever used one, once I’ve go the file and its live how long before G will drop it's listing of the page.

The page has some information but is only relevant to existing customers, for anyone else it wouldn't make much sense.

I could take you several weeks depending on how long it takes Google to reference the robots file and then update its search results, if you have a Google webmaster control panel it has a section where you can test your robots.txt file to make sure it's configured correctly.

This will also show the robots file content once it’s been referenced.

How can just one page affect your ranking or page rank?

Lots of things can affect your site and the page rank; look at the page in terms of relevance to the rest of the site, the content and the terms you’re trying to promote.

You shouldn't use nofollow for blocking the search engines because Google still indexes the page; it just doesn't make the link contribute to the target's PageRank. Also, other sites could link to the page without nofollow tags. Nofollow is solely for the purpose of avoiding link spam.

Using a robots.txt file is the only proper way to do it really, and the search engines do respect it.