Hello Steven,
what linecard is the 10GE port on ?
What IOS are you using ?
We had to upgrade IOS from 12.2(18)SXF11 to 12.2(33)SXH2 to correctly support 8 TenGiga linecard.
We had some strange problems like STP towards an access switch and error messages about the MEtropolis ASIC that is specific of that linecard.
We opened a TAC SR and they suggested us an IOS upgrade that fixed these problems
Hope to help
Giuseppe