Hi vfw,

The 7260 is validated for the M6800 so it's not a compatibility issue. Can you try removing the installed Intel driver/software and installing the Dell ones instead?

http://www.dell.com/support/home/us/en/04/product-support/product/precision-m6800-workstation/drivers (they are listed under Network)

If you get the same issues, is it possible to try the card in your other system and see if you get the same errors or not?