Live Ubuntu neither Live Kubuntu works?
 

I downloaded the both live iso, Ubuntu and Kubuntu, checked both MD5SUMS, and checked cds. but I can't boot anyone of them. Booting from cd starts and runs, but after
detecting hardware and begin to load from cd, then "retrieving libcb-vdeb" is showed, it gives error, saying that element can't be loaded. Anyone can tell me where is the secret?
(I used Suse live DVD, and Knoppix 3.6 without troubles).
About my hardware: MB= Asus K8N, processor= Sempron 3100+, vga= nvidia fx-5500, ram = 1Gb
THANK YOU

I have had trouble with the Ubuntu live cd before. As you said md5's checked out but always failed. I ended up redownloading and the second download loaded without a hitch, so you could try that. Also, burning at the lowest speed also helps for reliability.