download of version 11.04 won't auto run

I am running Ubuntu version10.10 satisfactorily. Downloaded version 11.04 to my hard drive and burned to a DVD. Went to run the new version but received the following message:
Error running Software, cannot find the autorun program.
How do I check if this program has downloaded to my hard drive image correctly. There is an autorun inf file showing as present. Or do I need to bin this Download and try again. I am worried the same could happen again . How do I ensure I have the full and complete download before burning to DVD.