Here is the error window you will see:

Please close all of your applications currently open (Photoshop, etc). To remove this error message, please remove the following two files which are parts to the onOne Library:

onOne Library.dll
onOne Library.acel.8bx

These two files help create the onOne menu. These files are in the following location:
Windows: \Program Files\Adobe\Adobe Photoshop CS4\Plug-Ins

Please [...]

The following are reasons why this error occurs.

An image is not open in Photoshop
The file type (image type) is not supported by this product
PhotoFrame is being launched when an adjustment layer is selected

If none of the above reasons apply, please close Photoshop and reinstall the product.

If you do not find your product listed below please contact customer service.
NOTE: Please DO NOT use the below download links if you are interested in a trial version of the products. Please click here to download a trial version.

Plug-in Suite 5
Macintosh – Current version 5.1.1
Windows – Current version 5.1.1
Plug-in Suite 4
Macintosh – Current [...]

The following products will support the 64-bit version of Photoshop CS4 (Vista and 7 only).

Plug-in Suite 5
Genuine Fractals 6.0.4 (Standard and Professional Edition)
PhotoTools 2.5 (Standard and Professional Edition)
PhotoFrame 4.5 (Standard and Professional Edition)
FocalPoint 2
PhotoTune 3

If you have older versions of the above plug-ins and a 64-bit computer and version of Windows you can still install and run the 32-bit and [...]

Please launch the onOne Software plug-in from Photoshop. Once the plug-in has launched, please choose the deactivate option from either the HELP menu or Photoshop menu inside the plug-in. Please DO NOT choose to remove license.  Removing the license will make your license code completely inactive.  Once you have deactivated from one computer you can [...]

The license you agree to during installation allows you to install on to 2 computers for all products made by onOne Software. You will also be able to load on either Macintosh or Windows. If you need to install on to more computers please contact sales for more information.

To prevent this error from appearing, please follow these instructions.
Please create (or have your IT department) an exception for the web IP address, name and port below. Once you have done this, please run the installer again.
www.ononesoftware.com
209.162.184.76
standard web  port 80

For Vista you will want to try to go to Local Disk (C:)\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup.  See if there is a shortcut to the registration program for the onOne product that is asking you to register.  If you see a shortcut called Register (onOne Product Listed here) go ahead and delete it.

NOTE: If you are not able [...]

This is an error with the Install Shield program.  Go to C:\Program Files\Common Files and there will be a folder called InstallShield.  Rename this folder to InstallshieldOld.  You will want to restart the computer.  Once the computer is back up and running try running the installation program again.

If one of the images you have selected for the Export is a Raw file this error can occur.  This is due to the plug-in not being able to create a Raw file.  You will want to change the export option to not save the file in the same format as the original.