Hi Paul
As per the SAP stranded you have to set the memory 70% Application & 30% Database.
1. In your MS SQL server memory resource should not cross more than 30 % of memory? If it is yes, you can set the memory parameters in MS SQL MMC
2. Balance amount 70% of memory can be used for application & OS
3. You can restart the system check the transaction code ST02 memory & buffer usage Is this any swaps?
4. Check the DB over all usage? refer the SCN link how you can fine trun the DB?
Tune your SQL Server SAP Database
Regards
Sriram