AveoSam..
Goto..Start - Settings - Control Panel - Printers & Faxes.
If theres more then one Lexmark in there you'll have problems.
Right click on your Lexmark printer and from drop down click "Delete".
If there's more then one "Delete" all printers.
If you did that already and No Go you could reinstall the drivers/software and then try to uninstall.
If that didn't work do a search on your computer for "Lexmark" and delete all files it finds.
Open "Regedit" and do another search for Lexmark and delete all keys.
I've seen computers with people's last three or more printer drivers still in there computers with out problems.
If you already know/did this sorry to waste your time...