Can’t share a printer to home workgroup

Upgrade my Win XP Sp1 to Win XP SP2 now I can not see any resource of the other workstations. All the computers are in the same workgroup MSHOME. . When I was in the Windows Explorer I was able to see my workgroup, but when I tried to expand it I got this error message: “[workgroup] is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions. The network path was not found.” How do I grant networking permission to this machine?