Then something is wrong with that xp pro setup on that flash drive.
What I should do:
- buy an external cd/dvd drive (or use one from a friend)
- buy an original Microsoft issued holographed Windows XP SP3 CD (Home or Pro), retail version, with a license key that can be used
- download all XP drivers and other needed programs from the Asus-site
Then install XP from that CD using that drive. Then install all downloaded stuff in the prescribed order.
Sorry, that's the only way to use that laptop again with Windows. Installing Ubuntu is cheaper and might work also.