Is Works running in the background? It is associating itself with something in your startup, from the sounds of it.
If you know the location, try e-mailing yourself a copy, sometimes that is a work-around. Another thing to try is opening Works and seeing if you can access it from the recently used list.
Also, look at the file location - if it is in a Works folder, move it to a document folder or you desktop and see if that cures it.