Pages constantly vanishing then reappearing in SERPs

[speedshopping]

Hi,

Does anyone have any experience in a domain or subdomain where its pages will rank naturally for a few weeks, then literally drop out of the sky for a few weeks, then reappear back to its normal ranking position, and then fall again etc.

I have had a good look in Analytics and will continue to do so until we find some kind of pattern, but wanted to ask if any webmasters had found a definitive reason as to why this keeps happening, or is it just plain random?

Cheers,
Wesiwyg

[canuckseo]

I've seen this when starting link building for a new site - but it usually only lasts a few days - not weeks.

That or if the domain is new I've seen this too - new site will be there then drops - sometimes it returns but in many cases it does not. Not sure if that helps?

[speedshopping]

the site in question is 5 years old, it started happening at beginning of 2011 and has been coming in and out of serps ever since.

[canuckseo]

Have you had any performance or stability issues - ie site offline for an extended period of time? Are you making a lot of changes to the site?

[levo]

Are we talking about only some of the pages?

[speedshopping]

No stability issues, no major changes apart from changes we made following first major disappearance which made no difference - we are talking sitewide drops in the nature of 100,000 pages.