Drop in traffic due to phrases used?

[cecilio]

Our Google search-driven traffic dropped to a third of its usual level. A large number of pages are still being indexed and all else seems well. We have a lot of products on our site so our search traffic is usually made up of lots of searches of different keywords. So e.g. for 300 hits, at least 250 will all be for different keywords - so it's not as though we've dropped for one particular key phrase - rather lots and lots of them. We are still getting some of these hits but just nowhere near as many.

There are 2 things I can think of that may have caused this:

1. I changed our Special Offers page to a Hot Deals page - could this have given Google issues with our site - would it have perceived this phrase as spammy?
2. We have been recategorising the way we organise our products - we've only done a little but could this have caused issue?

Is it likely to be one of these things or is there something else I should be looking for?

Thanks

[Swindler]

probably the second reason seems more probable

[suichiro]

I changed our Special Offers page to a Hot Deals page

I supposed this means that you have made a change on your content. A total change on that content might be the most possible reason why your site dropped its ranking on a particular keyword.