Sounds like the download manager symptome.
You should check the MD5 sum (available on the DL page, includign a tool for doing so) in order to see if the installer actually is corrupted or if the problem is your computer. If it is corrupted, then try downloading it without a download manager. Might also be a MIME type problem (the browser might think it\'s text, and convert the LF chars to CR+LF, obviously damaging the binary file). Force binary mode if possible.