Unable to install OpenSuse for the first time

Hello all, I've been trying to install OpenSuse on my PC, but I am having problems with it. I have Windows 7 and I want to change it into linux because it works too slow. I downloaded the .iso file from software.opensuse.org (full DVD- direct download). I burnt the .iso file with Astroburn lite in a DVD and everything was ok until then. I rebooted, changed my bios so it would boot first from the dvd and when it says: ->System Analysis: Initialize software manger, an error pops up:


"YaST2:
Unable to create repository from URL:
'cd:/?devices=/dev/disk/by-id/ata-TSSTcorp_CDDVDW_TS-L633C_R7256GAZ706576'
Details:
Unknown error reading from 'cd:///%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00?devices=/dev/disk/by-id/ata-TSSTcorp_CDDVDW_TS-L633C_R7256GAZ706576'.
History:
-Encoded string contains a NUL byte.
Try again? Yes No"
If I click No, the same error appears again, if I click Yes then another window pops up saying:
"YaST2:

• CD-ROM
• DVD

So, I click OK and then it says: Insert CD1 of Open Suse. I don't know what it's referring to. So, I finish the whole installation and it says 'Failed to initialize the software repositories. Aborting the installation.'


I then decided to click on Check Installation Media and when the process finishes: "Checksum wrong. This DVD is broken."
How can I solve this? Should I burn the DVD again at a lower speed or I have to download the .iso file again?.