If the unit was purchased with the intention of using it primarily for RAID, then the problem needs to be isolated so as to ensure that a solution may be provided. Removing the HDD and using it separately doesn't achieve that result ... it would be better to simply return the product.
The challenge is that the DNS has issues and hard drive manufacturers have issues. The problem could be entirely DNS related, entirely HDD, or an incompatibility between both.
IMHO, 'markbowman' suggestion to use the HDD separately was not an attitude as much as a sign of frustration experienced by many folks as a result of unclear marketing/sales information and slow technical support response provided by D-Link.
In D-Link's defense, they experience the same challenges that other companies experience - short product lifecycle VS return on investment VS customer retention.
Cheers,