not booting....please help

[lancer]

well i recently downloaded backtrack because i'm interested in network penatration. i made a usb dive using unetbootin and it has worked great untill i tryed to install backtrack on my hdd....something happpened and grub failed so i got my windows boot disk and ran f/disk mbr and deleted the linux partitions useing winodws disk manager i still have my bootable usb drive and now it wont boot....i get something like
ERROR:unable to locate ioapic for gsi i forget the numbers beside "gsi"
ERROR:unable to locate ioapic for gsi
ERROR:unable to locate ioapic for gsi
ERROR:unable to locate ioapic for gsi

and then it goes to a busybox shell. at first i thought my usb drive had corrupted the files and then i tryed it in two other computers and they booted backtrack fine.
please help, i usually find the answer online but i cant find anything that helped me.

Thanks, Lance H.

[KMDave]

Did you try to reinstall Backtrack onto the USB stick?

[lancer]

yes that dident work

no, I've tried that multiple times... I've searched for days and days on this problem...