For future references, you could just give yourself Full Control to the Program Files folder.
That'll also fix it for any other programs that might have the same issue.
To give yourself Full Control, do the following (Assuming that you're using Windows 7:
* Right click the Program Files folder, and select Properties
* Click the Security tab
* Click the Edit button
* Click the Add button
* Type your login name, and click Check Name. It should change the name to YourComputerName\YourLoginName and become underlined.
* Click OK
* Highlight your login name in the list
* Tick the Allow field for Full Control
* Click OK until all windows are closed again.