Standard advice: use the md5sum.exe tool, which you can find on the download page, to check if the files you downloaded are correct.
If not, redownload that file.
Don\'t use a download manager if you are, they can corrupt your files.
edit: also, about that .rar. I\'ve heard that firewalls can cause .rar files to download incorrectly. Try disabling your firewall, if you have one, when downloading them.