smp crash under network load

Folks,
        I have just brought my dual PPro up in mp mode, now when I do
any moderately heavy network traffic the machine drops to ddb with a
message of:

 "ex0: uplistptr was 0"

this message is not unique, I have just seen it using a UP kernel
built from the same sources but in the UP case the error is not fatal
and requires a lot of network activity to have it come up once.  In
the MP case the error happens almost as soon as the network traffic
starts.

-- 
Brett Lymn