Deleting Installation Folder

I recently reinstalled PW after a computer reformat on Windows Vista. When I downloaded the game client the install files were extracted to a folder on my desktop. Now that the game is installed, I want to delete the installation folder. However, when I attempt to do so, I receive the message:

"Destination Folder Access Denied. You need to confirm this operation." (buttons: Continue, Skip, Cancel)

Clicking Continue brings up another message saying:

"You need permission to perform this action." (buttons: Try Again, Cancel)

My computer only has one user account on it, so I obviously have administrator-level access. How do I get it through my computer's head that I have the permission to delete these files?

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On a similar note, I also receive a "This program needs your permission to continue" message every time I boot up PW. I've never had trouble running it so the message is never anything more than a minor annoyance, but it seems the two problems are similar in nature so I may as well ask about that as well.