Can anyone tell me what is a fatal exception,On closing down sometimes a blue screen appears with the message .. a fatal exception at OE(the a load of numbers),below it says press any key to continue,or CTR,ATT,DEL to restart computer, After doing either of these computer either turns off or restarts depending on which keys I press,. Then other times computer turns off normally,doesn't seem to be any adverse effect at the moment,but it is an old pc.

I've had this with mine and it aint old. :(

It could be some service in Windows that is having problems shutting down. Have you installed anything new recently, or updated anything? Do you have anything running constantly like file sharing software or BBC iPlayer or anything like that? Try stopping every program that you can see running in the task manager before shutting down to see if you can identify what is causing the problem.

"Fatal exceptions" arise when some program somewhere tries to do something it really shouldn't. The CPU catches the program in the act and goes in the huff, leaving Windows to clean up the mess. In this case "OE" means "page fault", which is geek speak for trying to access memory that the program isn't allowed to access. Someone, somewhere will have had the same problem; the hard bit is finding the solution amongst Google's twenty million results!