There has been a limit in Windows of 255 (or 260?) characters, as discussed in the SO question http://stackoverflow.com/questions/1065993/has-windows-7-fixed-the-255-character-file-path-limit .
There apparently is a way in Windows to get around it, and there might be a way with SAMBA to emulate this, but this may break certain applications.
For ease of management, unless you have a compelling reason not to do this, I'd see if you can try creating shares deeper into the file hierarchy so the path isn't so long, use subst or an equivalent to a symlink to shorten the file path, or reorganize the share structure so it's not so deeply embedded. This would make the most compatible with a variety of applications; less likely to run into program errors down the road.
There is a patch/change to the source that can be applied to SAMBA that a recompile would fix, if you Google around for it. But again, that can be an administrative issue later because updates may break your custom fix.
Another alternative is to mount the share as an NFS share. I don't think the same ~250 character limit applies to NFS, but it won't be quite as "Windows" a solution if you do it this way.
Personally I'd restructure the share to have fewer characters; least headaches and random issues down the road to remember why something might be acting up or stop working.