I had a script running on my site that would allow users to search for jobs. I had no idea the script was caching each and ever search and then Google was indexing these. By the time I found out - my site looked like a web spammer and I had tossed tens of thousands of thin content pages into the SERPS. So fixed it, redesigned site, went from HTML to wordpress.
Panda hits. I decided (stupidly) to use the script again since users really liked it and after talking to the developer of the script. He told me how to empty the search cache and make sure Google didn't index the searches. Well....he was WRONG.
Again.... I have an issues of thin content, cached searches into the SERPS. No matter what we tried Google was indexing them. So this was over a year ago. Google is STILL finding these pages in THEIR cache - thousands and thousands of them and calling them crawl errors.
Even after a year I am dealing with these pages - even though they've been long gone.... maybe even over a year.
Only after I started marking them as FIXED did they start going down.
I don't know if any of this helps you BigK - but just thought I'd share.