Why Does Google Replace My Website Pages?

[Reggie]

Hi All,

Can anybody shed any light on this issue I have?
My site is on the first page for most of my many keywords, but Google will replace pages for no reason, I will try to explain.
My home page title has 3 keyphrases (I have used keyword research tools to determine the most searched keywords within my niche) I also have good fresh content to complement these title keywords, The home page ranks on the first page in Google for all three keyword phrases, But every now and then Google will replace it with a second level page with the same search term, The title of the second level page is written within a different phrase (but still has the keywords within the phrase). This will show in the serps for a few weeks the be replaced by the homepage again. The page that was there in the first place (home page) just totally disappears from the serps.
My question is:
If Google thinks both pages are good enough to be in top ten (at different times), Why aren't both in top ten or even top twenty at the same time???????
Google doesn't seem to place pages in the serps on there own merits?
Why does Google replace one page with another?

 

[xiaofxia]

not to pick on Google because I think the world of those folk, but their HTML samples could be cleaned up a bit, usually, so I've also recast it as proper XHTML rather than somewhat sloppy HTML

 

[waggy]

Can you not put a tag in in bots display this page?

 

[Zebs]

I think that's just google algorithm working its magic. All in all your SERP rank isnt going to remain the same always, sometimes it will slip now and then could be due to something you do or could be something google does on their side. Since we don't actually know google's algorithm its impossible to say.