I had this same issue and reburned the ISO on a different media type and I didn't receive this error anymore.

I ended up using a memorex 8x dvd +r dl 8x, but I burned it at 2.4x

Dan

I would suggest using the no cashe install and watching it.  I had an issue with the network dropping out halfway through the install.  All I had to do was disable and reenable the nic and the install continued without issue.

Give that a shot, worked for me....

I was also using the beta 2 on Kubuntu.