Launching SQL Optimizer gives an "There is no disk in the drive. Please insert a disk into drive (4249813)

When I launch SQL Optimizer from Toad, I get the following error message.

"CSDispatcher.exe - No Disk
There is no disk in the drive. Please insert a disk into drive D:."

1) Un-install SQL Optimizer.
2) Download the SQL Optimizer installer from www.quest.com.
3) Re-install SQL Optimizer using the installer from Quest's website, instead of using an installation CD.

Here are instructions to download the installer from Quest's website:

1. Visit www.quest.com
2. Go to Support|Downloads & Updates
3. If you have a Supportlink account already, log in.  If you do not have one already, click the "Register" button and follow the instructions to register.
4. Type SQL Opt in the product search field, choose Quest SQL Optimizer for Oracle from the drop down list, and click GO.
5. On the left, under Product, choose 7.4.1. 
7. Click the installer name on the right to download.
8. Choose which directory you would like the installation media to be downloaded to.
9. Once download is complete, go to directory that has installation media.
10. Double click on icon and follow installation instructions.