SMB Permissions Issue
What I'm Trying to Do:
Utilize File Sharing with SMB enabled on an OS 10.8 Mac Mini to allow Windows and OS X machines on my home network to access a folder stored on an external USB drive.
What the Problem Is:
My primary goal is accomplished with the exception that rebooting my Mac breaks SMB. When I attempt to access the SMB share via Windows 7, I receive a prompt indicating that my credentials are incorrect. The only way I have been able to resolve this is by turning off the File Sharing feature in Mac OS and then turning it back on. Suddenly, all of my SMB shares can be seen and accessed once doing this.
My Question:
Why does my SMB functionality break every time I reboot the Mac? How can I prevent this from occurring in future reboots?
Mac mini, OS X Mountain Lion (10.8.2)