I get this every once in awhile as well. Typically, what I do when I get it is log in to that server to see what's going on. Everything is always normal.
I believe what happens is the alert is created and it is just a snapshot of the system at that moment. And some times it just happens to take a snapshot when the system is under a heavier load than normal (ie. clients sending logs to the SEPM, SEPM downloading LU contents, SEPM pushing LU contents to client, clients heartbeating in, etc.)
Did you log in to the box to what was going on? Run process explorer on it to see what the load is currently.