flashdrive (linux boot drive) is randomly dismounting

okay, I am running Ubuntu off of an 8GB flash drive. i am doing this on a HP netbook. today, something really weird happened that has never happened before... at one ish, in was minding my own business watching a youtube video out on my front lawn ( "borrowing" neighbor's internet FYI). then firefox stopped responding. a few seconds later everything else stopped responding. i could still move the mouse and stuff. but then all of the icons on the computer dissappeared and a message box popped up when ever i clicked anything... only i could not read it because it only showed little boxes where the text was supposed to be... i then looked at the flash drive because i remember this happing once before when some A**hole unplugged the flash drive while linux was running.
the drive was still in the slot, but the led was flashing like when you first stick it into a computer or when the drive is completely idle...
this went on for a few minutes until i finally cut the power.
when i rebooted i noticed the battery was at like 35% so i just decided to turn off the computer and go in to let it charge.
3 hours later i came back out and went right back to youtube... after about an hour it did it again!
after i rebooted the battery was around 38% ...
 this time i immediately went into power preferences to make sure that none of those nasty spin down hard disks when idle options somehow got turned back on... they were off (all of the battery power saving options were off too because they annoy me)

this is very weird because this just started today! i have been using this setup for several months now without any problems at all!

does anyone know what is causing this all of the sudden? or better yet how to make it stop doing this?