Hmmmm I'm not sure I don't see anything obvious.

When was the last time you did any routine maint. on your laptop.

It would be a good idea to run disk cleanup and disk defragemter.
These can be found 1) start 2) all programs 3) accessories 4) system tools. It sounds like you have a nice laptop and it would most certainly appreciate this.

Also I didn't see how much RAM you had.

One other question are you running any other programs at the time this occurs? Make that 2, how long after you start d/ling does it freeze up?