Has it ever bothered you that there isn't an obvious way to remove the previous items in the Run box in Windows? It's often very useful, of course… but if you are just a little bit paranoid you might want to clean out that list on occasion.
Of course there are many cleaner applications that will do this for you, but we'll explain how to do it manually.
Clear Recent Run Dialog Entries
Open up regedit.exe through the start menu run box, and then navigate down to the following key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU
You'll see all your recent commands on the right, and you can delete any of the keys that contain your commands. You'll have to logoff and then back on, but the list should be clean.
Note that this will also work for Windows Vista's Run dialog, although most people have switched to using the search box instead.