Single page vanishes - some new kind of penalty?

[MikeNoLastName]

This one's been driving me crazy all day. I have exactly ONE page that's been affected. It is still in the index, but last week went from about 8 to 7 to 5 for an extremely popular search term, then today just plummeted to nowheresville. I have lots of other top 10 SERPs for even more popular terms in the same domain. It is one of my traditionlly busiest pages, and pretty much a standard in its niche (it also has light G Adsense). I can find it by PART of the words in it's title, but not by the ENTIRE title. It can also be found using MOST of the EXACT title with punctuation (The title has a hyphen and commas in it BTW).
i.e. the title is like: A B C - d, e, f g
"A B C d e" finds it,
"A B C d e f g" does NOT find it.
"A B C - d, e, f" DOES find it!

It is about 75K in size (it's a very long reference listing) and has not been updated since May 8. It was last cached by G on May 20.
There is definitely some sort of penalty in effect here, wondering if it has to do with too many keywords in the title or punctuation in the title?
Interestingly, another site's page with a title very similar, but definitely different just showed up in the top 10 under the same terms.

[RichTC]

Mike,

A PR7 site of ours had a similar experience. A popular two word search for blue-widget listed the site at position 4 for its blue-widget page which was a PR5 - in our opinion it was the most relevent listing in the entire top ten compared to what was listed near it.

Anyway, The page vanished completely for a week, then a different page for the site but with the blue-widget keywords on showed up in position 18.

Two weeks after that the original correct page came back and replaced the position 18 one, a week later it moved up a little more to about 14.

The site page now ranks position 7. The entire cycle had taken about 5-6 weeks.

I have similar examples, the bad news is if the PR of the pages concerned is lower it takes longer, from what ive seen and is all related to the missing pages issue - see the other thread on the subject

[MikeNoLastName]

Not to reply to my own post, but I've just made some additional observations after the self edit expired. Regarding the plummeted page, Gbot has still hit it at least once a day since the 20th, but the cache is still 5/20. It can also still be found very high ranking for phrases like "popular popular unusual". Definitely some penalty targeting on very common or high competition terms, I'd say. It is a PR5 linked directly from a PR6 home page (and many others lower) but I just noticed when listing backlinks fo it, the home page is NOT coming up anywhere on the list! Maybe an omen, maybe not.

Also been noticing some very odd Gbot activity concerning some of my #1 ranking pages. For a page with a name like abc-def-ghi.htm I see it searching for abcd-ef-ghi.htm, abc-edf-ghi.htm, abc-def-hig.htm and so on over the course of a few days. I double checked to make sure these weren't my own typo mistakes on links, but Gbot seems to be the only one following (or making up) those particular links in all of my log!

[tedster]

Mike, this "little" observation about a single page vanishing may be a key to something important - a change in the spidering or indexing pattern for example, or possibly a single page ban/penalty. Do you have any knowledge of something that might look funny about the page? 75 kb of html is pretty big, but I've got some bigger and so far no trouble. And a PR5 page linked from the Home Page does not fit any other pattern we're talking about here.

Googlebot does invent urls at times, just like a doctor may at times hit you on the knee even though he's a healer. It's usually just a check-up to see how your server handles bad urls. However, I've never seen small variations on one of these check-ups before. They've always been completely "from left field" urls.