Anyone familar with Samba 3 and it's permissions caching?

Currently the issue that I am have is the following.

A samba share is defined. You set the permissions to the samba
share. In the previous version of Samba (before Samba 3) the
permissions take in affect in real time. Restarting the service was not
necessary. With Samba 3 you have to restart the smb service each time
you change anything in the /etc/group or the directory permissions.

The windows users accesses the share initially and cache the
permissions. Upon changing the permissions on the linux side (directory
and /etc/group) and not restarting the smb service the user still has
the previous set of permissions.

Has anyone else come across this issue? Is there anyway to flush the
cache so that the service does not have to be restarted each time?