Do not confuse the DefaultAppPool application pool, which appears by default when you configure a computer to run in worker process isolation mode, with the MSSharePointAppPool application pool, which appears by default when you install FrontPage2002 Server Extensions or SharePoint™ Team Services from Microsoft.

Note

Do not use, delete, or make changes to the MSSharePointAppPool application pool. It holds files that are used internally by FrontPage Server Extensions and SharePoint Team Services.
может это наведёт на мысль!? :)

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Если дела идут плохо, есть вероятность, что в ближайшее время они пойдут ещё хуже. :)