This is a very uncommon problem, since it's well known Windows only supports being installed on an internal HDD or SDD and not on a flash drive, so nobody (except you) does that.
All I can advice: get your Windows 7 install disk and do a startup repair. What happens with Windows XP on the flash drive then? Can you still boot from it?
Next time you try this, disconnect the hard disk with Windows 7, so you're sure it isn't touched in any way.
ok so i was trying to install xp on a flash drive and this has happened twice once 3 years ago and once now, i selected the partition for the flash drive when installing xp etc, but when i installed xp on the flash drive, it messed up my main hard drive on windows 7, now when i try to load from the hard drive it says it can't find the boot information, it doesn't blue screen, i'm pretty sure the computer now thinks windows 7 is windows xp because when i give it a 2nd OS option from a flash drive it shows two windows XP options, how do i fix this? everything from the hard drive is still intact
last time i was doing the same thing and it's like it installed another version of xp even though once again I'm sure i selected it to install on my flash drive, two different computers not even same model, now i'm on a toshiba netbook, this doesn't make any sense, how could this problem even occur? i'm probably done with all windows OS at this point and i'm switching to linux but i would like to get on windows 7 from the OS one last time because i want to do things with my internet cookies etc
anyone have any advice? this must be a fairly common problem, i'm sure i selected the install drive to be my flash drive, so how does it mess up my main hard drive OS? it should have never touched it