How did you partition your HDD? Do you use your old HDD?Sometimes HFS+ may NOT erase completely,--especially when it once formated as NTFS-- you can choose to repartition your HDD, rebuild partition map and erase with 10-times mode(requiring longer time to accompilsh)Above all,make sure you have checked the MD5 of your DVD ,set your HDD as active Primary partition(I suggest IDE) and chosen the right components in your "customised" installation.

Anyway,you must tell your hardware details in your signature.

Good Luck!!!
Regards!!

Kael