Okay, so when you are on the 2008 server, and double click on the optical drive, you receive the message "access is denied". At first, I thought you meant clients from other PCs were not able to access the server's optical drive.
What is the make and model of the optical drive?
Take a look at Event Viewer and look at different logs for any relevant error messages.
When you installed the
driver, are you installing it as administrator?
And when you say switching users, you mean logging out and logging back on the 2008 server, correct? I want to make sure no client PCs are involved.