This is a Path/File access error, and happens when the software isn't allowed to write to a particular file. There may be many reasons for this.

You're running Windows 7

There is a special feature in Windows 7 called UAC, that prevents files from being written without authorization. To turn it off, go to the Start menu and type "UAC" into the search box and press Enter. In the window that appears, drag the slider all the way down to turn it off. You will have to reboot your PC for the settings to take effect.

Note that UAC should have been turned off when installing your software. If you have to turn it off after the software is already installed, your software settings will have to be reset.

You don't have access to the file

When the machine is being operated in an unreliable environment, such as a school, the system administrator may not allow access to the hard drive. Please make sure that the computer user has full access to the installation directory.

Read-only setting

If the file being written has "Read-only" permissions set, the software will be unable to write. This can happen if the file is copied off a CD. To change the permissions of a file, right-click on the file and select Properties. At the bottom of the file, there is an Attributes section. Ensure that the "Read-only" checkbox is not selected, and press OK.