Looks like the software files are losing the attributes that specify type and creator, so your computer doesn't know what to do with them. These can get clipped in transit - that's why apps dl'ed from supplier's sites are further protected by binhex or Macbinary.

See my answer under "limewire document" http://www.gnutellaforums.com/showth...?threadid=7799 for more info. I'm not sure where you'd find the correct type/creator info - perhaps get a trial version of the same program?