Annoyance runs amok

For the past week or so now, google has indexed our entire site, listing up to 150 pages! But then... sometimes under a few hours, or even upon a page refresh, they remove all the listings again.

And I'm not even talking about pages that are identical... pages that are similar only in the header, nav links, and footer, everything else (up to a page worth) is completely different. I've checked out a few other websites, ones that have content that's virtually identical on pages -- and they have all the "identical save three words" pages listed, so it's not that... Sent off an e-mail to google, to try and see if they have any reason, if they can provide a reason, since nothing in the help files says "I'm listed for one hour, but then I'm not again, but within the next five, I'm back, but then gone again -- but google hasn't used the bot on my site during the time, and it's the same pages coming and going." Nothing like that at all there. Perhaps it's a glitch? Who knows... All I do know is all the non-google search engines (major ones) have hundreds of pages indexed and listed, and 98% of our hits come from them, 2% come from google... and probably from me checking out the few timeouts that are listed (amounts to 0.0001% of the total pages).