problem with running virtual xp from usb

hello,

my hard disk was damaged , so i wanted to run a fully functioning xp from usb till i buy a new one, im working now on an ubuntu from usb , anyway ,i saw some tutorial out there about booting vhd , i made a vhd file using virtualbox ,installed xp on it,copied it to another flash disk, defragmented it, and i run it throught grub4dos, it shows the blue screen just a millisecond after the xp logo, i checked the tut again and i seem to forget to install winvblock after installing xp on the vhd file, or lets say idont know how to do that so i skipped it , is that the cause of my problem ,if so then where to dl it and how to install it,

thnks for your time