Msseces.exe Excessive CPU

Msseces.exe is part of MSSE. I'm noticing that on some machines it run
excessively, so much so that I'm taking it off those machines and replacing it
was Avast. Now I'm getting excess CPU on one of my own machines.

If I kill Windows Explorer (that is, the user interface) and restart it from
the Task Manager, it loads up everything fine, including msseces.exe and I
have no further problem.

Does anybody here have a clue as to why msseces.exe is hogging CPU on some
machines and not on others? On other machines it's silent, and just
occasionally blips a little here and there.

Again, as is usual with me, I'm looking for REAL ANSWERS from people with
experience dealing with this, not speculation on what MIGHT be wrong.

Thank you.