This error usually means a program is looking for this ddl in your system somewhere else (like if its in the path folder like system32 or something). Because of that, it creates an error. You'll have to dig a bit to find out about it.
Another good thing is to make sure you don't run anything when you try to install that downloader. CTRL + ALT + DEL and go to process and applications and remove anything unwanted. If your not sure then don't do it cause you might mess Windows up but if you feel like messing with it, go ahead. But I warned you.