This problem is reproducible with the FileExplorer control only when is set with a thumbnails view-mode.
This is expected behaviour of ASP.NET. In the following links you can find more detailed explanation and a possible workaround: http://blogs.msdn.com/b/johan/archive/2007/05/16/common-reasons-why-your-application-pool-may-unexpectedly-recycle.aspx http://stackoverflow.com/questions/2248825/asp-net-restarts-when-a-folder-is-created-renamed-or-deleted?lq=1 Also, a custom content provider utilizing PhysicalPaths and SharedFolders can be used to overcome this behaviour: http://www.telerik.com/support/kb/aspnet-ajax/editor/details/use-radfileexplorer-with-physical-and-shared-folder-s-paths