Hi,
We cannot reproduce this issue with our environment.
Please try to eliminate the cause one by one.
To confirm that you can access the folder or not with following pattern.
1) Connect PC to the NAS directly, then you try to create share folder and access it by using NASNavigater.
(do not use router and HUB).
2) Connect an another PC to the NAS with the same IP segment, then you try to create share folder and access it.
3) Temporally turn off the firewall and anti-virus software, then you try to create share folder and access it.
When you can access a share folder by any of those pattern, The unit is working fine.
Please check network configuration and environment.