I had tried to run backtrack 5 r3 from usb and i faced this problem at the end of the black screen: "---[ end trace .... ]---
kernel panic - not syncing:attempted to kill init!
[sda] attached scsi disk" ,where backtrack freezes and wont response.
I tried to reinstall it,but nothing changed.
I have formatted usb to fat32 and have used unetbootin.
however,after two days searching on the internet,the only way to use backtrack on usb is use the latest version of backtrack( kali linux https://www.kali.org/) I knew that when this message appreared "cannot load a ramdisk with an older kernel image",that means the computer hardware Does not match with the backtrack version. this problem can exist on many computers,not all of them.