My 600m (bought in September '03) went down the other day.  Whenever I try to reboot it, the cap lock LED will blink 10 times and then the computer turns itself off.  I tried the following. 

Firstly, I saw that the fan wasn't running.  I removed the keyboard and tried to cool the CPU with a cup (a stainless cup) of cool water.  Woo, the computer was able to run and load Windows XP.  After being quiet for a few minutes, the fan kicked in, although not as loudly as normally does.  Then, I removed the cup, and in a few seconds, the computer froze.  I tried this processes several times, every time, the fan was able to kick in, but as soon as I move the cup, the computer would freeze.  After probably four times, the computer can no longer reboot and the cap lock light keeps blinking. 

Could anybody interpret what could went wrong?  I heard that the 600m model can even run without the fan, although at a slower pace.  So, maybe there're more serious issues? 

Thanks for any information.  This 600m has been very sturdy.  The only thing I had to replace in the last five years was the memory.  Hopefully, I can fix it this time.  I have plenty of time to play with it.