Weird Ping Issue on 3com Netbuilder router

[networkman12480]

When I ping our main frame relay router, a Netbuilder 227C running SW/NBRO-CF,9.1 firmware. It gets its LAN feed from a Nortel 8100 switch. This problem propagates across the frame relay circuit to the far end router (another 227C running 9.3 firmware) and Nortel 450 switch connected to it. See below ping times. Note that the avg. 3000ms ping response occurs after every 12 normal pings. What could be causing this problem? I've run Wireshark on both ends to see what kind of traffic might be causing this issue, but it looks pretty clean except for an SONMP (Nortel Discovery Protocol) broadcast every 10 seconds from the Nortel switch, which could just be coincidental...
See below--

Reply from 172.27.251.1: bytes=32 time=3062ms TTL=29
Reply from 172.27.251.1: bytes=32 time=4ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2990ms TTL=29
Reply from 172.27.251.1: bytes=32 time=4ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2ms TTL=29
Reply from 172.27.251.1: bytes=32 time=2989ms TTL=29