Try uninstalling the current driver and then visit the printer's manufacturer website and install the driver for Windows (32-bit or 64-bit as mhelm1 said). If there is not a Windows 7 driver available, you can try installing the Vista driver in compatibilty mode. If you provide the make and model of the printer, we may be able to provide you with more information.
Cheers,
Cassandra
Microsoft Windows Outreach