Dell 3115 scan to network computer

So we have a 3115cn set up to scan to ten different computers using SMB. Scan functionality was spotty at best (due to improper settings mostly) before I completely deleted the address book and started over. I set everything up using port 139 and username/enabled password, etc. set to scan to a shared folder called "SCAN" directly in the root of the hard drive. All this worked wonderfully for a month or so. The only complaint was one user occasionally (like once every two weeks) got an SMB error (I didn't ever see the code or I would include it), requiring him to disable his network card and reenable, and it would be resolved. This morning, in an attempt to resolve this nuisance, I changed a few settings and viola! the error changed. I stopped getting an SMB/FTP error and started getting login error 016-782. I recently, in an organizational effort, changed all the computer names and IPs of these computers, so i feared I had broken the scan functionality for all ten machines (even though I changed the IPs on the scanner's address book; believe me, I have double and triple checked these, they are correct). I tested every one, and 3 of 10 are coming up with error 016-782, so it's really unlikely that this is due to my IP/computername changes.

I noticed on one of the 3 computers that the shared "SCAN" folder's shared settings had changed, so I changed them back, and I once again found massive success in the form of the error message changing. Now, still getting a login error, the error read: 016-783. Usernames, passwords, and IPs are all correct on the 3 computers which can't scan, and all the settings are exactly the same as teh other 7 machines. I tried disabling the antivirus with no success, and, similarly, all 10 computers are using the same antivirus with the same exact settings. At this point I see absolutely no reason these 3 should be unable to scan when the other 7 work fine. Any suggestions that I haven't already tried? I have also tried deleting the 3 individual address book entries and recreating them from scratch.