Hmm, well most likely, they're tracking cookies, which, for the most part are harmless.
What is a good idea to do, however, is run CCleaner every week or so.
Directions for this:
Begin by downloading CCleaner, and specifically choosing the most recent version.
Then, follow these steps:
1. Close all programs so that you are at your desktop.
2. Double-click on the "My Computer" icon.
3. Select the "Tools" menu and click "Folder Options".
4. After the new window appears select the "View" tab.
5. Place a checkmark in the checkbox labeled "Display the contents of system folders".
6. Under the "Hidden files and folders" section select the radio button labeled "Show hidden files and folders".
7. Remove the checkmark from the checkbox labeled "Hide file extensions for known file types".
8. Remove the checkmark from the checkbox labeled "Hide protected operating system files". 9. Press the "Apply" button and then the "OK" button and shutdown My Computer.
10. Now your computer is configured to show all hidden files.
Now, install the program. Open it, and choose the 'Options' tab. Inside, hit the 'Custom' tab, and add the following folders (Note: Not all of these files are on every computer. If one of these isn't present, skip it):
C:\Windows\Temp
C:\Temp
C:\Documents and Settings\<Every user listed>\Local Settings\Temp
C:\Documents and Settings\<Every user listed>\Local Settings\Temporary Internet Files\Content.IE5
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