Tablet crashes when in base for extended time

[ptdunl01]

Whenever I have my X61 tablet (Vista-32) in the dock for a while, and there are 3-4 applcations running (games, video, etc.), the computer does this shut down-crash thing. It doesn't RESTART, it just crashes. When I manually restart it, there are no signs that anything is wrong. I've been told that it could be overheating, but is there anything to do about that IN THE BASE? I've also heard it could be the motherboard (???). The last three times I've tried to play my game, it's crashed right in the heat of battle...Any ideas?

[Od]

I get the exact same unexpected shutdown, no matter if I am using the dock or not. Sometimes the laptop just decides to shut down and when I manually start it again it seems like nothing unexpected have happened - just like when I manually shut it down.

It always crashes when I am playing a game (WoW), when I am trying to watch a movie on an external screen and sometimes I just return to find my laptop shut down, when I left it open, in power, and with all sleep/display/hybernate options off! 

I am using a Lenovo X61 Tablet with Vista on it, and it was formated two days ago (after getting a blue screen permanent problem that couldn't be fixed and the laptop would never start)