Buffer overfill problem

[Dirton]

Hello, we use a couple of HP ProCurve 2510-48G switches as our core switching nodes, so they are critical in term of network stability. We noticed that on one of them sometimes packet buffer gets overfilled that result in missed packets. Here's "show system-information" output with 70 days uptime:

Packet   - Total   : 3022
Buffers    Free    : 2774
Lowest  : 0
Missed  : 33,372

We decided to track down what causing the problem by tracking those numbers in time. We recently started using zabbix to monitor our network, so I decided to use its' ability to track SNMP values, but unfortunately can't find any of those values represented in SNMP OID's. Could anybody help me out on this?

And should we start worrying with those numbers at all? And how can we lower them without impacting switch functionality? Mainly we need only support of VLANs.