Help with bandwidth bottleneck

Please help troubleshoot this issue.

Setup: We should have a 1gbps burstable. Fiber comes in to the Cisco router which then feeds to a Cisco stack in the DMZ. From the Cisco stack we feed to our HP Procurve core switch with a two port trunk. All ports are 1000FDx

Situation: Here's where it gets tricky. From the Cisco stack we have the gig burstable. From the HP core switch we only manage about 100mbps.

I figured the problem was clearly the trunk or possibly the cables we use for the trunk. Tried new cables, bypassing the trunk with a direct feed from our router to the core switch on a new port. Even tried a direct feed from the router to a different gig HP switch. All results were 100mbps.

I'm not sure what else to try. I"m not seeing any crazy collisions or anything to warrant concern on the HP switch, but something is affecting the feed to the HP while not affecting the feed to the Cisco stack. Is there some possible port setting on the Cisco router that isn't available on the HP end and is creating a bottleneck?