Reboot itself when converting the files

[Hamiksaiaja]

Hi,
Can anyone please h elpme to identify the problem that I experience it.

The problem is when I am converting .rm files to avi or wmv using the video conversion software, when its on halfway (around 20 minutes), my computer restart itself. Anyone can help me to identify the problem please. I have tried a couple of different software already, but still experience the same thing.

Thanks in advance