I have a similar issue on two different machines. Originally I could copy pretty much any file to my usb flash (fat32), but during one of the updates I ran, not sure which, I could no longer copy ANYTHING to my flash on either machine. I do understand the various answers, IE: bad usb slot; bad flash, etc, but it used to work on BOTH machines, and now I can't copy from either. I also CAN copy FROM (UGH) win7 to linux on my dual boot (win 7/linux mint 13) machine, but NOT vice versa. I've tried about everything, including other format types on several flash chips. It absolutely cannot be that they are ALL bad, just as it cannot be that 9 different usb ports on two different PC's could be bad. There was/is a bug somewhere in one of the Lord knows how many updates that Linux Mint has installed that made it all go to hell in a bucket. There isn't any other possible explanation. The only thing I can think of is a reinstall on both machines, and then, as tedious as it may be, to do all the 200+ updates one at a time. This, however is ridiculously impractical, and I certainly am not going thru all the formatting issues I had to plod thru to get the dual boot installed in the first place. Odd how Linux Mint 13 WILL copy files (music, AVI, text, etc) FROM Win 7, but not vice-versa! You may blame hardware all you like, but that cannot be it on two different units!