Rankings disappear after first search, even with all history disabled

[seovin]

when I search for some keyword in Google, it shows my site in first page. But, if I try to search again then I'm not able to see my site in first page(in fact not even in 20th page)...
It is happening for past 2 weeks continuously...

I have not logged in to any google account and i have disabled web history in toolbar, cleared all the cookies...

If any one knows the reason, Please let me know. Looking forward for your reply.

Thanks for your reply in advance!

[Robert Charlton]

Hi seovin, and welcome to WebmasterWorld.

Do subsequent browser sessions (ie, closing the browser and reopening) return your site to the first page? When and how often in the process are you flushing cookies?

And does your search include location specific terms? This appears to me where Google has been most aggressively applying personalization.