Recently I have taken all my data backup from ubuntu (laptop) to windows xp (desktop) to re-install OS in laptop. But ironically, filezilla ftp client transferred all images, pdf files, doc files in asci format.
As I read on this, ascii format means, it strips off 8th bit of every byte (this bit used for a special purpose flag). Restoration may not be possible.
See a sample, how I lost lot of data, print screen image of jetspeed tutorial page (in pdf)