Windows 7, ReadyNas NV+ disappearing files on share

Windows 7 Ultimate, 64 Bit
Ready Nas NV+ : 3 - 1 TB drives
Using 'User' access.

I first had a 'shared' share that I had setup for guest access.
On my Win 7 machine I wanted to add it to My Documents and My Pictures, but it would not until I setup it up for off-line folders (I believe so it could be indexed).
I did that, but then started noticing that any drive I had connected to the NV+ using guest access would randomly lose access to all the files that were NOT synchronized - even though the drive is there and continues to function fine from other computers.

What funny is that I can look at it, find a file, go back in a few minutes and the folders and files disappear. I can sometimes hit the drive again and they will appear again. I can hit the drive I have mapped and am using username access with no problem. When I turn off synchronization I again have no problems.

I do have the settings configured as per the following issue:
faq.php#Why_am_I_not_able_to_access_ReadyNAS_share_that_is_password_protected_with_Vista%3F

Thanks