Temporary Files ~DF*.tmp

I regularly carry out disc maintenance (usually once a week) running Disk Cleanup, Chkdsk, Disk Defragmenter, and searching for and deleting *.tmp files.

Recently, on searching for *.tmp files, I found a large number of files of the format ~DF*.tmp in the directories:-
C:\Documents and Settings\[username]\Local Settings\Temp

These have only appeared during the last few days. For each user, there are two of these files for each logon time and each are 32KB in size.

Does anyone know what creates these files and why they are not automatically deleted on logout?

I am running Windows XP Home Edition SP1, and the only changes I have recently made to my system are:
3rd May - Installed Microsoft AntiSpyware (Beta)
10th May - Installed Windows Malicious Software Removal Tool - May 2005 (KB890830)
11th May - Installed Microsoft Windows Rights Management Service Client with Service Pack 1
15th May - Updated Adobe Reader 7.0 to Version 7.0.1

PinguJohn, I have noticed those same ~DF*.tmp files in the same location on my XP system since I downloaded & installed the Microsoft AntiSpyware (Beta) Program. I have been deleting them with no problems. Windows won't let you delete the ~DF*.tmp files with the current date. I'm assuming that the files are used by the Microsoft AntiSpyware Program for one reason or the other. You will be able to delete the files with today's date tomorrow.

Tufenuf

Thanks for your reply Tufenuf.

I can confirm your suggestion that the files are used by the Microsoft AntiSpyware (Beta) Program because if you shutdown the program then you can delete all the ~DF*.tmp files including the ones with the current logon time and date.

I wonder if Microsoft are aware of this?