my page's location in the Google search results lower than before

[chavdar]

Why is my page's location in the Google search results lower than before?

3 months ago the site was in Top 10 and from yesterday totaly dop to 41-50
What can be the problem?

it is a PR5 site and PR is still 5
I have about 30 new pages with similar meta description, could be this the problem, or google see this as duplicate content may be?

How often Google change the SERPs? Can i a have again TOP 10 SERPs with modified page content , titles, description etc.?

When every single page of my site apears lower than before what can be the problem, change in algorithm, low backlinks or google sees duplicate content?

[edited by: caveman at 10:08 pm (utc) on July 24, 2006]
[edit reason]
[1][edit reason] Removed URI, per TOS [/edit] [/edit][/1]

[LifeinAsia]

First, don't post URLs- it's against WW's charter.
Second, just because you have a certain ranking in Google doesn't mean you're going to keep it forever. Third, just because you have a certain ranking on one data center doesn't mean you will have the same ranking on all of Google's data centers (they have hundreds of different DCs, some of which have slightly different databases).

If you search WW, you will find many threads about lowered rankings on Google durign the past few months.