O/S Memory Consumption Issue

Hello,

I am using SQL Server 2008 R2 SE installed on WIndows Server 2008 R2 SE. I recently installed a third party tool to monitor the SQLServer and I am seeing O/S Memory Utilization in a critical state. The server has 56GB of Installed memory of which 32GB is usable. Hence for the Maximum memory setting of SQL Server I assigned was 28GB. Now to get rid of this issue should I lower my max memory settings assigned to SQL Server to a lower value?

Thanks.