external hard drive problems

hi i have a buffalo ministation, have been using it for months with no problems, i have got loads videos and pics on it so dont want to lose them.

i went to use the hard drive to day but every time i went to load it up it froze and then came up with a message to re-format the hard drive. but have been told if i do this then i would lose all my stuff. also the blue light that normally stays on now flashes on and off....any suggestions??? i have tried putting it in another usb slot but no different. when i go it to the control panel to look at the hard drive a bit more it says there is no problem with the hard drive and the light then stays on???

many thanks jack