How to allow “Guest” account sharing between Windows 7 & XP:

1. Launch gpedit.msc from Start Search box.
2. Locate to

Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment\

3. In the right pane, double-click “Access this computer from the network”. Click on “Add User or Group”, add “Guest” in the list.
4. Double-click on “Deny access to this computer from the network”. Select “Guest” and click Remove.

If the issue still occurs, please temporary disable firewall on the Windows 7 computer.