>That line of code game me an "Unknown name" error

Just check if the syntax corresponds your container hierarchy. The keyword to add to the object reference is ".object"

>And no, the image list was added last.

Imagelist is supposed to be added to Form before the control which is going to use it.

>I'v done this many times before, with no problem. Why it doesn't
>work now is anyones guess.
>

Did you install anything on your PC recently? Check if an updated version of imagelist/listview was installed. You may try to compare date/size of files containing the controls on PC where it works and on yours.