scan problem in photoshop 7 - please help

i have a problem when scanning in photoshop 7. each time i try to acquire an image, photoshop automatically disappears! the window just shuts down, sort of crashes (although i see when i click ctrl+alt+del that it remains opened in memory, along with twunk_16) and i get no image whatsoever. i had psp 6 and then moved to 7, but i had this problem previous to that, i thiunk when i reinstalled windows.
i use file - import twain to scan. i believe it's either a problem with photoshop or with twain. i'm sure it's not the scanner as it works perfectly on software from the scanner package, such as (crap) scan button. but, i can't do anything quality if i don't have it with photoshop. any ideas? please let me know! i've tried everything, really... nothing works. i need a solution urgently as it affects my job.

- Federico