Win7 pc can see network pc’s but cannot access shares, why?

On a network with 15 pc’s, all Win7, 1 ’03 server all was well until we added another Win7 pc that shares a data drive. 14 of the pc’s can see the new pc and access the share. One can see the new pc but cannot access it. All 15 pc’s are identical. If I log on locally to the pc that cannot, ie not the domain, I can see and access the share. There is only one domain user name that is used on all of the pc’s and no group policy has been implemented that could cause this problem.