A significant part of sql server process memory has been paged out. This may result in performance degradation
http://msmvps.com/blogs/omar/archive/2007/09/19/a-significant-part-of-sql-server-process-memory-has-been-paged-out-this-may-result-in-performance-degradation.aspx
From here you will come to know about Performance Counter Settings, CacheSet exe in Windows, Setting Working Set during Startup and Microsoft PSS blog link