First, unplug your printer from your laptop.
Go into System Preferences and click on Print & Fax. If your printer is there, delete it by selecting it and press the ( - ) icon at the bottom.
Plug your computer in your laptop and un Print & Fax, press the ( + ) icon and select your printer.
Try to print from there.
If you have Snow Leopard, the drivers will be installed automatically. If you have a older version, you will have to download the right drivers from lexmark.
Hope this helped you out!