I bought a Lexmark X1290 printer and installed a wrong driver (for WinXP) from the enclosed CD. Then I could not run the All in One program. After many reinstallation attemps, I finally found a solution (which is unfortunately quite hidden at the Lexmark website):
1) Unplug the printer's USB cable from the computer.
2) Download the cleaning utility from ftp://ftp.lexmark.com/driver/inkjet_drivers/Cleanup/
3) Double-click on the cleanup utility and follow the on-screen instructions to run it.
4) Restart the computer.
5) Download all files from ftp://ftp.lexmark.com/driver/inkjet_drivers/Cleanup/reg/
6) Follow the instructions in the "Vista BackDoor Instructions.txt" and delete all remaining Lexmark
keys in the registry.
7) Restart the computer
8) Download a proper driver for Windows Vista from the Lexmark website.
9) Install the driver accordingly to the instructions (it's important to plug the printer's USB cable when you are ask to, not before)
The problem with Lexmark Unistall and CleanUp Utility is that you cannot delete all Lexmark registry keys while you arelogged in the system. This is anellegant way how to circumvent the problem.