The answer to your question:
"Debug dump files" are copies of the contents of your computer's memory.
When a program crashes, it will sometimes "dump" some or all of the
contents of RAM to a file on your hard disk. The file is only useful to
a technical support person who is trying to understand why the program
crashed. (Most tech support people have no clue what to do with a dump
file.)
Unless you've been asked to submit a dump file for inspection, feel free
to get rid of them....."
http://answers.microsoft.com/en-us/windows/forum/windows_xp-performance/debug-dump-files-and-setup-log-files-in-disk/71569bd2-c212-480b-abd0-c14d68c95cce
And how to clean these files--See excerpt below:
"Windows Error Reporting creates several types of temporary files that are used for error reporting and solution checking. Once you've resolved any problems, or if there are no current problems, you can delete these temporary files. You can clean up temporary files by completing the following steps:
1. Click Start→Programs or All Programs→Accessories→System Tools. Then select Disk Cleanup..."
http://oreilly.com/pub/a/windows/2007/03/06/cleaning-up-your-disk-drives-in-windows-vista.html
Good Luck.