If I'm not mistaken the thermal limit for the R40's is somewhere in the high 70's C. So 52 is just fine. I annoyed at Laptops running so hot myself, as the way I have my desktop setup it hardly every sees 40.
Infact there is a utility (the name of which escapes me now) which we use to check temps on the laptops, and generally what you will see when running it at full blast (running prime 95 or something) is that the temp will creep slowly up, even while the fans are running full blast, then when it hit's the thermal ceiling, it will automatically scale back it's speed to like half or so, until the temp comes down a couple degrees, then it will kick back up to full speed and repeat the process.
But the problem you're having sounds like a bad mainboard, that is generally the only time when it just shuts off. I would suggest you bring it to the helpdesk as soon as possible so we can that fixed for you, and also take a look at your groupwise problems.