1. The message is thrown when the site is restarted by few reasons. A modification of web.config (when web.config is modified and saved .NET restarts the application so the changes can be applied)
Add new frontend language from Administration->Settings->Languages, when new language is added Sitefinity is automatically restarted because there are lots of changes occurring in all modules to incorporate the capability to add content in one more language version.
The application pool is recycled due to reguilar recycle or when the memory limit for the application pool is filled up the pool automatically recycles to free the memory.
2. The system is restarting message is not generated by Sitefinity it is comming from .NET framework. I don`t think it can be changed, I was searching for a way, but didn`t find any.
the Telerik team
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