Try edditing your host file by adding the ip-address and machine name. Had the same problem wich was solved after i eddited the host file.
Location of the host file: C:\Windows\System32\drivers\etc
After i editing the host file but i still can't access to the window7 pc. could you should me for example that need to be done in host file? such as: this is what i am setting but it still ask me to enter the password when i try to connect to window7 pc. and i am using window xp and try to connect to window7
# Copyright (c) 1993-2009 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
192.168.1.6 Rayh # Ray PC
# localhost name resolution is handled within DNS itself.
192.168.1.6 Rayh
# ::1 localhost