Can't save from Win7 to smb share

I have Win7 connected to a SMB share on the server. It can view files, copy files, and even overwrite files in the share. All works, except -

if I open any program such as word or adobe, then try to save from the menu to the network share, I get errors, usually:

There has been a network or file permission error. The network connection may be lost

I had a similar error with smb on a linux box, which is exactly why I tried to switch to osx server. Same error.

I've tried turning off op locks and turning on strict locking, messing with permissions, etc. Nothing seems to be working.

Any suggestions?