HD problem on MBP 13"

[dannys95]

I recently got me a MBP 13". I'm pretty happy with it's specs (for now) but wanted a bigger hard drive. So I went and got Hitachi HTS723232L9A360 . It's working fine....but theres one problem that's been going on since I installed this new HD. Every so often the screen will just blink. Sometimes it blinks and the whole thing freezes up for a few seconds, then comes back to normal. It's a weird problem, and apparently only happens while I'm on OS X (or Snow Leopard now). I tried installing the new update and it says my Mac does not need it. Is anyone else having this problem? Any fixes? Thanks.