The PolicyKey [1] continuously scans your system to ensure it stays within the requirements set by the HSU network security guidelines. If your system goes out of compliance for any reason - for example, if you have not patched your OS or have not updated your antivirus - your system will be quarantined from the network until you are able to fix the problem.
Links:
[1] http://www.humboldt.edu/its/glossary/5#term136