Различие между сбросом веб-сайта IIS7 и остановкой веб-сайта IIS7 / запускается

To completely clear out bad settings in memory you should perform an application pool recycle. That restarts the actual w3wp.exe worker process.

Restarting the website is a brief change that doesn't really restart the app pool. Stopping and starting must be long enough to allow the app pool to stop, but it's not consistent either.

To recycle the app pool, find which app pool your site is using with the "Basic Settings" link under the Actions pane. Then from the Application Pools section you can restart your app pool.

Check out Week 16 of my video series. It explains app pool recycles in more depth.

As for the actual root cause, Debug Diag is a good tool that will allow you to get a memory dump when the issue occurs. That will hopefully give you enough clues on the root issue.