• What kind of alert? That the OS is low on memory? How low?

    You have max memory set but that only pertains to the buffer pool. Did you check to see if SQL Server is using an increased amount of non-buffer pool memory over the last 4 days? This can be caused by things like Linked Servers, large execution plans, SQLCLR processes, among lots of other things.

    There are no special teachers of virtue, because virtue is taught by the whole community.
    --Plato