if complete data loss isn't a problem...
i'd try to nuke the first few MB of the drive:
Code:
dd if=/dev/zero of=/dev/sdX bs=1M count=10
has helped me before in similar (?) situations.
if that doesn't help, just let it wipe over the whole drive:
Code:
dd if=/dev/zero of=/dev/sdX bs=1M
sdX has to be replaced with your usb drive, without partition numbers.