Unable to access files/folders moved to share root thru CIFS

I'm having a permissions issue that appears to only be affecting CIFS.

When I create a new file/folder within the root of a share or copy a file/folder from my desktop to the root of a share; I can access it as one would expect too.

However, If I move an existing file/folder that is located within folder on the share to the root of the same share; I lose the ability to access it through CIFS. When I attempt to access it, I receive the message below.

Network Error
Windows Cannot Access \\NAS-xx-xx-xx\share_name\folder_name
You do not have permission to access \\NAS-xx-xx-xx\share_name\folder_name. Contact your network administrator.

However, I can still access these files/folders using FTP/S or HTTP/S.

This occurs with new files/folders or pre-existing data already residing on the share. In other words, if I create a new folder named 'folder_1' in the root and then create a new folder named 'folder_2' and a new file named 'testfile.txt' within 'folder_1' and then move them to the share root, I'll no longer be able to access them using CIFS. I'll still be able to access and fully manipluate them using ftp/s and http/s though.

Checking and then appling the 'Set ownership and permissions for existing files and folder...' on the Share's Advance Options tab restores my ability to access them through CIFS. However, this doesn't fix the problem as the next time I move a file/folder to the share root, my access to it using CIFS is once again lost.

After encountering this, I installed the EnableRootSSH add-on to see what is happening.

If I create the following structure through cifs and ssh in; the ls cmd reports (note I can access everything here):

\shared\
.......|-\folder_1
...............|-\folder_2
...............|-\testfile.txt

drwxrwxrwx 4 admin users 4096 2011-11-28 07:26 /c/shared
drwxrwxrwx+ 3 tom powerusers 4096 2011-11-28 07:29 /c/shared/folder_1
drwxrwxrwx+ 2 tom powerusers 4096 2011-11-28 07:26 /c/shared/folder_1/folder_2
-rwxrwxrwx 1 tom powerusers 1 2011-11-28 07:28 /c/shared/folder_1/testfile.txt

or depends on share

drwxrwxrwx 9 admin powerusers 4096 2011-11-28 07:17 /c/support
drwxrwxrwx+ 3 tom powerusers 4096 2011-11-28 07:28 /c/support/folder_1
drwxrwxrwx+ 2 tom powerusers 4096 2011-11-28 07:28 /c/support/folder_1/folder_2
-rwxrwxrwx 1 tom powerusers 1 2011-11-28 07:28 /c/support/folder_1/testfile.txt

After moving 'folder_2' and 'testfile.txt' to the root of the share using CIFS, ls shows the following (Can no longer access folder_2 or testfile.txt)
\shared\
.......|-\folder_1
.......|-\folder_2
.......|-\testfile.txt

drwxrwxrwx 4 admin users 4096 2011-11-28 07:26 /c/shared
drwxrwxrwx+ 3 tom powerusers 4096 2011-11-28 07:29 /c/shared/folder_1
drwxrwxrwx+ 2 tom powerusers 4096 2011-11-28 07:26 /c/shared/2
-rwxrwxrwx 1 tom powerusers 1 2011-11-28 07:28 /c/shared/testfile.txt

or depends on share

drwxrwxrwx 9 admin powerusers 4096 2011-11-28 07:17 /c/support
drwxrwxrwx+ 3 tom powerusers 4096 2011-11-28 07:28 /c/support/folder_1
drwxrwxrwx+ 2 tom powerusers 4096 2011-11-28 07:28 /c/support/2
-rwxrwxrwx 1 tom powerusers 1 2011-11-28 07:28 /c/support/testfile.txt

Note that the tom user account is a member of the 'powerusers' group and a secondary member of the 'users' group.

I admit that I'm only a couple of rungs up the ladder from a noob when it comes to linux. I read SPHARDYs overview of ReadyNAS permissions, SPHARDYs Guide on how to setup ReadyNAS Permissions and bert386's Guide. The best I can tell, is that I have things configured properly.

Any ideas on how to correct/resolve this?

My System Info
NAS: ReadyNAS Pro Business Edition, RNDP6000-100NAS with RAIDiator 4.2.19
Clients: Windows 7 Ultimate SP1 x64

My Accounts and Groups:
I have 5 user accounts and 2 groups ('users' and 'powerusers'). Two of the accounts are members of the 'powerusers' group. These accounts are also secondary members of the 'users' group. The other three accounts are members of the 'users' group only.

Shares:
I have 7 shares (not including home shares). All of shares including the home shares are experiencing this issue.

Each of the shares is configured identically except for the group defined for each.

all of the shares are configured for CIFS, AFP, FTP/S, and HTTP/S.

My CIFS share configuration is:
Default Access:...............Disabled
Read-Only Users:.............Un-checked
Write-Enabled Users:........Checked (User field is empty; group field is set to either 'users' or 'powerusers')
Allow guest access:..........Un-checked
Share Display Option: .......Un-checked
Recycle Bin:...................Un-checked
Automatically set Permissions on new files and folders:..........Checked
Do not allow ACL changes to be more restrictive than this:......Checked
Folder Group Rights:.........Read/Write
Folder Everyone Rights:.....Read/Write
File Group Rights:............Read/Write
File Everyone Rights:........Read/Write
Opportunistic Locking:.......Un-checked

Advanced Options
Share folder Owner:...............admin
share folder group:................users or powerusers (depending upon the share)
Share folder owner rights:........Read/Write
Share folder group rights:........Read/Write
Share folder everyone rights:....Read/Write
Grant rename and delete privileges to no-owner of files:...........Checked
Advance Share Utilities- Shift share content timestamps by:.......0 minutes
Set ownership and permissions for existing files and folder:.......Checked and applied

Regards,

Tom