I have a Dell and when I went to install the printer CD I got the invalid drive E message. I went to disk management but it only shows C drive so I don't know how to change the drive letter now.

I'm not sure if that will fix your problem but to change a drive letter:

1. Open "Disc Management"
2. Right click on the drive you want to change.
3. Select "Change Drive Letter and Path".

Hope that works.