X1 Carbon Incorrect Hash Errors during OSD

I was fighting with this one for a couple of days.  Lenovo X1 Carbon - deploying Windows 7 x64.  All drivers were fine and dandy but I was getting randon "Incorrect hash value" errors when the OSD was failing.

This was determined by looking in the SMSTS.log once the OSD had failed.

It transpires that if the USB to Ethernet adapter was plugged in to the right hand USB socket it was dropping loads of packets.  Plugging it into the left hand side worked a treat.

As simple a solution as it sounds this may be far too obvious for some tecchy to even try.  I managed to replicate this on 3 different units so it wasn't just faulty parts.

Felt like a complete numpty once I discovered the fix!