i have a fully functional install of BT4 on my laptops harddrive

and i also have a fully functional install of BT4 on my 32gb thumbstick

when i try to boot off of the thumb drive (i know i'm booting off of my thumbdrive and not my laptop because my thumb drives grub menu is in a different order) and i 'startx', the desktop that appears is from my hardrive installation. and if i delete a file from the desktop, and then boot from the harddrive, that file is gone

my thumb drive works fine when i boot from it from my windows machine, it has its on desktop with files i put there, and persistence is fine. but when i boot from it on the machine with bt4 on its harddrive, it always seems to load from the harddrive after the grub menu and not from the usb

at least thats what i think its doing

any ideas?