Cannot boot from usb external drive

I recently created a GParted live usb disk on my pen drive according to instructions and tested it in other laptops. But my inspiron 1501 with phoenix bios (2.6.3, latest) wont boot from that. I have changed the boot order with both "Removable Disk" and "USB drive" above the hard drive. I even used the same method to make my external hard drive bootable but still it does not boot from that! If my system cant boot from external drives why is the option there ?

My cdrom drive does not work for a long time and every time i need to boot from some other source, i need to pxeboot, and thats troublesome. Please help.