Why can't my Mac Pro connect to an SMB share over the network? I have a really weird problem. I have a Raspberry Pi running an SMB server that shows up in the sidebar of the Finder. I usually can just click on it and connect. Just today, it stopped working and gives me the error "Connection Failed". It has worked fine in the past. I'm running OS 10.8.4 on a Mac Pro. Our MBP (also 10.8.4) connects just fine, no problems. I see log messages in Console.app as such:

9/10/13 7:14:43.869 PM com.apple.kextd[12]: Request from non-root process 'netbiosd' (euid 222) to load /System/Library/Extensions/smbfs.kext - not allowed.
9/10/13 7:14:43.870 PM netbiosd[84]: Loading com.apple.filesystems.smbfs status = -603947004


Thoughts?
First, try to restart File Sharing in the Sharing Preference Pane.

There is a bug in OS X that still lives in 10.8.5, where a race condition can cause File Sharing to start before an auth configuration is done, causing it to fail any SMB connection to network shares with any sort of privileges.

If this solved your problem, one way to automatise this process is to create a launchd agent with the following contents:

&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;
&lt;plist version="1.0"&gt;
&lt;dict&gt;
        &lt;key&gt;Label&lt;/key&gt;
        &lt;string&gt;com.mcdado.restart_smb&lt;/string&gt;
        &lt;key&gt;ProgramArguments&lt;/key&gt;
        &lt;array&gt;
        &lt;string&gt;/bin/bash&lt;/string&gt;
        &lt;string&gt;-c&lt;/string&gt;
        &lt;string&gt;sleep 60;touch "/Library/Preferences/SystemConfiguration/com.apple.smb.server.plist"&lt;/string&gt;
        &lt;/array&gt;
        &lt;key&gt;RunAtLoad&lt;/key&gt;
        &lt;true/&gt;
&lt;/dict&gt;
&lt;/plist&gt;


Save this file to ~/Library/LaunchAgents/com.mcdado.restart_smb, then load it by running the following command: sudo launchctl load ~/Library/LaunchAgents/com.mcdado.restart_smb

Source: SMB and Lion | Oceanside Coding