Basically, if monitoring is not enabled during the installation of a satellite,
enabling monitoring will result in an environment not suitable for monitoring
(known problems: some needed and assumed data (like the default 'Panic
Destination' contact method) is missing from the database).  An example
traceback caused by attempting to create a general, check nothing probe attached.

To replicate:
Enable monitoring with a satellite not installed with monitoring.
Create a system probe, which will generate 500.