Error when attempting to install printer on Windows 2003 Server

[dsd17]

I'm having a problem attempting to install a print driver on my Windows 2003 Server machine. Every time I run the installer, it tells me 'Existing print driver may be in use. Please restart and try again.' I've restarted, but that makes no difference at all. it gives me the same message as before. I've tried deleting all of the files that were previously created by this installer (which did work up until today) and reinstall. No go. Anyone have any ideas?