Your notebook doesn't like booting from external HDD's, did you set the BOOT parameter in BIOS ?
I used a 40 gig external HDD and made a persistent bootable copy of backtrack 5 iso using universal boot Installer..
On my netbook.but as up I restart it bt doesn't load .inserting the same HDD on my desktop bt boots fine ..
Intel pentium 4
Boot order : DVD rom-USB-external HDD-HDD-Ethernet
Netbook(thinkpad x e100)
Ati radeon graphics card
Boot order : external HDD- USB -external cd /DVD rom-HDD
For wifi I would us my USB wireless labpn rtl-8187
I have a similar problem:
I saved the Gnome 32 iso to a usb stick and in my Bios I have that USB stick at the very top. When I restart the computer, it still skips over to Windows Vista (on the HD) instead of booting BT5. So, I tried moving the boot file to the root directory on the stick and still no luck. Then I moved ALL the files to root with no success.