Thank you for posting your question in the Microsoft Community.
Based on the information, you are receiving an error message when trying to install Lexmark Z25 printer.
It would be helpful if you could reply to these questions to assist you further.
1. What is the complete error message you are receiving?
2. How are you trying to install the printer drivers?Are you using a CD?
It seems the printer is not fully compatible with Windows Vista. In Lexmark support website, the printer drivers are only available for Windows 98, ME, 2000 and XP.
For further information, refer the Lexmark Support article: