Try disconnecting the network drive mapping (assuming that's what you have that you can 'see' the remote machine). Could be it's mapped with different credentials to those SE is using? Windows doesn't permit connection to a single \\Server from the same client machine (at the same time) with more than one set of credentials.
If you're not using a mapped drive letter, just being able to 'see' a remote machine in Explorer proves nothing. Can you browse a share on it? Edit a file in that share? That error message suggests maybe not.
If you're not using a mapped drive letter, just being able to 'see' a remote machine in Explorer proves nothing. Can you browse a share on it? Edit a file in that share? That error message suggests maybe not.