You will see the errors in the following scenarios:-
PC YamahaA tries to access PC YamahaB's shared resource \\YamahaB\xyz.
PC YamahaA tries to print on a printer YamahaB_PRN connected to PC YamahaB

Reasons:
What's probably happening is your PC YamahaA is using cached domain credentials when accessing the PC YamahaB. This generally happens when YamahaA belongs to a domain while the YamahaB belongs to a workgroup.

Solution:
The easiest resolution would be: I am using Win2k as an example for the navigation.
1. Share a directory in <YamahaB> say xyz
2. Go to My Network Places in <YamahaA>
3. Right Click and Choose Map network drive
4. Choose a drive letter and in the folder specify \\YamahaB\xyz
5. Click on Connect using a 'different user name'.
6. Enter the YamahaB administrator (or any YamahaB user that has access to the shared resource) and the password.
7. Depending on whether you need to retain the share, choose the 'Reconnect at logon'.
8. Hit 'Finish
9. You should be able to access the shared resource using the mapped drive.
10. Now try accessing the PC YamahaB as \\YamahaB
11. If you have the YamahaB_PRN printer shared, it should be visible now.
12. Connect to the YamahaB_PRN printer and update the required drivers.
13. You should now be able to print.