On the off chance that what I have here might spark an idea in someone concerning this often mentioned problem, here's a specific error:

I've got a home network with two PCs. Now with an eMac I Go>Connect to Server. I supply the username and password. Here's the result:

Code:
Connecting to smb://123.123.1.123/PCname...
Code:
The operation cannot be completed because one or more required items cannot be found.
Code:
(Error code -43).
I wonder if the source of the problem is something at the PCs, not at the eMac...?

Worked on this and that, and now the error is:

Code:
The Finder cannot complete the operation because some data in "smb://123.123.1.123/PCname could not be read or written.
Code:
(Error code -36).