posted 3/3/2010 by MikeMollenhour - Views: [2316]
Recently working for a client I had an issue where a little after sql was started and the memory got to approx. 50 % the whole OS (Windows 2008 r2) became unstable. This could be recreated easily and the OS would get so unresponsive the performance monitor (with just CPU selected) would leave blanks on the line drawing. Troubleshooting this was difficult since the CPU usage was low and Io was low and 50% of the memory was still available. Come to find out the OS must have been paging out SQL Buffer pool memory this was fixed by changing the group policy for the SQL server service here is a link to the MS Article
http://support.microsoft.com/kb/918483.