Different Yahoo Results for Different Browser Agents

[SWTechnologies]

I've recently discovered that performing a Yahoo search for the same keywords, but in different browsers, generates different results... Anyone have any ideas as to why this may be?

As an example, I recently performed a search in Yahoo for the key phrase: "automated storage capacity expansion".

Initially I did the search using IE 6 (on Win2000), then repeated the same search, but with the Mozila Firefox browser (again on Win2000) and received two completely different listings...

Very strange, very inconsistent! Does this mean Yahoo is generating 'browser specific' results? Any idea as to why?