I suspect this might be too specific a problem to find a quick solution here but I might be wrong. Try lexmark's support and if they have a 'contact us' link try that also.
Did you re-install from original cd? If so might be worth checking out their site to see if they have a more recent version of the software. (on the basis that some windows update might've broken it or something hence when you re-install it still doesn't work).