Be more specific.
What do you mean by "not happy"? Are all these issues happening when you have the Hitachi plugged in? Or are/were they separate from the problems you're having with the Hitachi right now? And more specifically, how is your computer reacting to the Hitachi drive being installed? Does the computer blue screen? Does it hang on load-up? Does it give you any kind of error that you can see on your monitor?
In order for us to help you, you have to be as specific as possible with the problem you are having. Tell us everything that happens. The more information we have, the easier it is for us to figure out the problem, and the quicker you get back to using your old hard drive again.