Thank you for choosing Fixya.com. Here's my suggestion:
- Go to the below mentioned link & download the uninstaller for MFC9420CN, Download this utility on your Desktop.
- Now unplug the printer & run this utility to remove the software from the Vista Machine
- Now reboot the machine & configure the computer in clean boot state.
to do that follow these :
To perform a clean boot on a computer that is running Windows Vista, follow these steps.
- Click Start
, type msconfig in the Start Search box, and then press ENTER.
If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.
- On the General tab, click Selective Startup.
- Under Selective Startup, click to clear the Load Startup Items check box.
- Click the Services tab, click to select the Hide All Microsoft Services check box, and then click Disable All.
- Click OK.
- When you are prompted, click Restart.
Once you have rebooted the machine, Try to install the Software.
Hope this would help.