Cursory questions per usual:
1. Did you check the md5 sum of the downloaded image?
2. What browser did you use to download the iso with?
3. If burning to DVD, what Windows application did you use?
4. If you burned a DVD, did you burn at the slowest speed your burner supports [and has your Burner ever been cleaned]?
5. Brand of DVD if DVD burned.
6. If USB, what application did you use to create the USB stick and did you format to FAT32 first?