The "5 minute summaries" are expected operation. There is a very clear write up on page 10-114 of the Access Security Guide (here is a direct link to Chapter 10 where this section is found:
http://cdn.procurve.com/training/Manuals/3500-5400-6200-8200-ASG-Jan08-10-ACLs.pdf)"The first time a packet matches an
ACE with deny and log configured, the message is sent immediately to the
destination and the switch starts a wait-period of approximately five minutes.
... At the end of the collection period, the switch sends a single-line
summary of any additional â denyâ matches for that ACE (and any other â denyâ
ACEs for which the switch detected a match). If no further log messages are
generated in the wait-period, the switch suspends the timer and resets itself
to send a message as soon as a new â denyâ match occurs"