1 of 2 things.

If you've just powered on the unit, or during the first few hours, it's quite busy gathering all the guide data and indexing it.  Give it some time before you hammer it.

It could very well be a bad drive and/or unit (something might have gotten knocked loose during installation).  If you've given it say 24 hours, and it still is acting like this, I'd power off the unit and double check everyhing, even scan the drive for defects. 

Glad you got it working!

Yes, while all the cool hacks/enhancements work, the poor machines only have so much horsepower and doing all the extra stuff, while normally is fine, it's quite labor instensive on the machines when they are first powered on as they're getting 12-14 days of guide data and indexing and processing all that info so you can start searching for programs and setup recordings.

I know it stinks sometimes as you get a new toy and want to play with it immediately, but it usually pays of to let it sit and hold off until it gets most of the indexing done first.