Printer Message from AutoCAD The plot device in the PC3 file cannot be found

See if the printer exist by going Start > Devices and Printers.
If it does not exist add the printer.

Uninstall and reinstall the printer.

If it is a add-on program like PDFCreator:
CREATE a system restore point!
uninstall Program from Program and Features uninstall program.
Delete C:\Users\Username\AppData\Temp.
Delete %temp%
Run CCleaner
look for keys in regedit and delete them
    HKEY_CURRENT_USER\Software\Software Name
    HKEY_CURRENT_USER\Software\Software Name
Run CCleaner