A large amount of memory is committed to applications and processes. Consistently high memory usage can cause performance problems. To determine which processes and applications are using the most memory, use Task Manager. Monitor the activity of these resources over a few days. If they continue to use a high level of memory and are less critical processes or services, try stopping and then restarting them. You can disable this alert or change its threshold by using the Change Alert Notifications task in the Server Management Monitoring and Reporting taskpad.
 
To modify the value, do the following:

• Click START -> Run -> mmc .
• Click File -> Add/Remove snap-in in MMC .
• Add health monitor and click ok back to the main screen.
• Navigate to Health Monitor -> All Monitored Computers -> SBSSERVER -> Small Business Server Alerts -> Core Server Alerts -> Allocated Memory.  On the right-hand pane, right-click on "Allocated Memory" and choose Properties.  Edit the "is greater than" value to reflect the correct amount of RAM.  Default is 2 GB/2147483648 (3 GB = 3221225472, 4 GB = 4294967296).
• Click OK to save.