K cool.
Now when you redownloaded, how'd you do that?  Download the windower again?  Did you uninstall windower from the add/remove programs first?  
When I delete the spellcast.dll file from the plugins folder, and reopen the launcher, it no longer says it's on, but has the icon for downloading again and then I can redownload.  Is yours the same?  Does doing that help?