[ubuntu] Ubuntu won't install!

If anybody could help me at all

I am trying to install Ubuntu 12.04.1 LTS and when I try to install it,it goes me this error

The ext4 file system creation in partition #1 of SCHI1 (0,0,0) (sda) failed.

Please help my drive is unallocated space and I have two partitions one saying "extended" and the other is "Linux-swap" and I'm booting off my USB

Please help :(