Welcome to TF!
That is interesting... I used to get something similar to that on my Dell Vostro 1500. But rather, if it was on battery at boot up, and it loads the Window's screen. Rather than freezing, it would turn the display off for a second, then resume.
Did you ever try to run out your battery, to the point where it shuts down, then recharge your battery? That's all I can think of at the moment.
Edit: Now that I think of it, you might want to take out the battery and rub the connectors with your fingers. (with your laptop off, of course) Might also want to take your power cord off and blast some condensed air into the power hole in your laptop.