I chased this around off and on for several weeks and finally stumbled upon the resolution so I thought I would post it here in case others are stuck on it.

SUSE Linux Enterprise Server 11.3
I was trying to get network windows servers to print through CUPS and kept getting numerous errors. After resolving the "nt_status_bad_network_name" issues by setting up a login ID in /etc/passwd of SERVER$ I made progress and finally got smbspool to connect to the windows print server. I was still receiving "/usr/lib64/backend/smb failed" error messages when attempting to print through CUPS. A listing of /usr/lib64/cups/backend revealed that there was a bad symbolic link for smb.

smb -> /usr/bin/get_printing_ticket

deleting the stale link and resolving it with a link to smbspool magically resolved the printing issues.

ln -s /usr/sbin/smbspool smb

Of course if you are not using 64bit Linux or SUSE, your path and links may be slightly different, but relinking the backend process should resolve CUPS not printing to a smb device.