Error Deleting File or Folder
Cannot delete [file]: Acess is denied.
Make sure the disk is not full or write-protected and that the file is not currently in use.

Annoying huh, here it is:

1. Open a command window. You can do this by going to Start -> Run and typing cmd. If you are using Vista, go to Start, then in the search field type cmd or command.
2. Now that you have the command window open, you'll have to set a schedule. To do this, type:
   

   at [time] /interactive cmd

   and press enter. It should say Added a new job with job ID = 1. Where it says [time], you type in the current time in your computer plus one minute, be sure to set it in military time! (For example: If its 1:26, you would type: at 1:27 /interactive cmd );
   -I hope you understand military timing.

3. Now, you have to wait one minute or a few seconds until a new command window appears. When the new command window appears, fire up task manager (Ctrl + Alt + Del), and end the process explorer.exe. (Go to the Processes tab. Select explorer.exe from the list then click on End Task) Now your explorer window should disappear, leaving opened the newly opened command window.
4. Now, on the window, type in explorer.exe, and your explorer windows should reappear with SYSTEM privileges; wait a few seconds while the SYSTEM user account is set up. Now you should be able to delete that annoying file of yours.

To get back into your own username, just login again.

Still having trouble? Please comment.