DW4 by Macromedia came out in December 2000. I think that ship has sailed...
If you mean CS4 which came out in 2008, contact Adobe Customer Service. They might be able to help you.
In the end, you might want to look at a Creative Cloud subscription which gives you full downloads to 17 products including Dreamweaver CS6 for $50/month.
Thank you. It is CS-4 (the DW with the current CSS included).
I had the opportunity to get a "deal" on the DW CS-4 and had been using it for a while. My computer went "south" on me and I lost ALL the programs that I had downloaded; which included the DW CS-4 and FW CS-4.
I will contact the Customer Service people on Monday for some kind of remedy.