Sometimes my computer comes to a halt and I look at Task Manager to see what is using up the processor. It is usually dumprep.exe. What is this and what causes it to come into play?

From Microsoft support...

The Dumprep.exe tool is a Windows XP fault logging program. If a serious error occurs, Dumprep.exe writes the error details to a text file. The Dumprep.exe tool then prompts you to send the error information to Microsoft. The Dumprep.exe tool is a non-essential system process that is installed for third-party use.

http://support.microsoft.com/kb/899870/en-us

Ditto to Tom's explanation of what it is. What brings it into play is some software not playing well with others and hanging up your system. It happens to me (XP Pro) occasionally with Expression Web software. Sometimes it'll kick in two or three times when trying to run things. I find if I restart the PC, it goes away.

My PC generally runs 24hrs a day and often some memory gets corrupted causing problems like this.

I upgraded (clean installed) two laptops to Win 7 and it is so much better than XP. I have one that is older and one newer, I found drivers without a problem for the older one and the newer one worked perfectly immediately on start up.

This file also shows up sometimes if you close a not-responding program from the task manager or if I.E. give you one of those, "I.E. must close errors." If you simply go into task manager and end the process on those dumps, you system will stop halting.

Big D