I did a fresh install of Snow Leopard on my Macbook and soon realized my Samba shares were broken through finder – but still worked from the CLI.
Worse still once I tried to access the shares Finder would basically be dead, you’d need to Force Quit it to make it work again.
Eventually I reached for tcpdump and wireshark and found it’s the pesky .DS_Store files again, seems my QNAP is denying access to them, Finder did not cope well with this.
A quick bit of hackery of my smb.conf solved it:
veto files = /.AppleDB/.AppleDouble/.AppleDesktop/.DS_Store/:2eDS_Store/Network Trash Folder/Temporary Items/TheVolumeSettingsFolder/.@__thumb/.@__desc/
delete veto files = yes
Once I got this removed and samba restarted my shares were working again in Snow Leopard. A bit annoying but not too hard in the end.

can you clarify how you fixed the problem. I get i/o error when using finder to move files between my mb and network drive using smb.
That did not work for me since I did not have control of the server that caused the problem. I had to do this instead to force Finder to not even try and create those peske ds store files:
defaults write com.apple.desktopservices DSDontWriteNetworkStores true
R.I. would you mind going into depth for an OSX newbie?
My issue is this: After the SL upgrade my shares to a Vista box work fine on boot. After a certain amount of time, connection to the Vista box dies and finder will not reconnect. It not only hangs on trying the discovery of the shares, it also prevents me from rebooting the machine properly.
I ‘su’ at the command prompt and have checked both the smb.conf under my local user account as well /etc/ but am failing to see the lines you have mentioned above.
Any help would be greatly appreciated. These SMB issues have almost driven me to downgrade.
Or try this in a shell: defaults write com.apple.desktopservices DSDontWriteNetworkStores true
I tried that first, didn’t seem to work anymore on the Snow Leopard finder – Its a complete rewrite, maybe somethings changed.