What does this mean, and why it happens,
I recently rebooted my server and it it stopped responding, I mailed to my host who said the server had gone into kernel panic

What exactly does this mean

Regards

As far as I know it can panic for a number of reasons but it will be beacuse it has got stuck and can't continue...

For example I managed to make a kernel panic once because I told it my machine had 256KB of RAM rather than 256MB of RAM (my mistake) and it just couldn't fit everything into it, hence it got stuck.

Have a look at what it says just before it paniced and that should tell you what the problem is. That was how I spotted what I had done wrong.

Hope it helps.

Can you tell me what files to check for the same

I had given the command shutdown -r and after that it happened

Regards

Well when I did it I watched it scroll up on the screen infront of me.

If it panics before it mounts the hard drive then it will not log anything to it. Or if it gets re-booted before the disk cache is written to the disk the most recent entries will be lost.

If it panics after that there might be a log of what happened in /var/messages (well that is where RedHat puts if by default on my systems)

The easiest way would be to connect a monitor but if the server isn't at your location that might be difficult. On remote servers I just try to be extra carful as I can't get to it to sort it out if something like that goes wrong.

I am assuming you have got this error because the boot configuration or kernel is differnet to before, can't you or some one that can access the server put it back to what it was before? Choose the originaly configuration off LILO or something.