Does this bug occur if you create the USB stick without persistence enabled? If not, then this could be fixed in Maverick and needs fixing in Lucid-updates, see https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/627672
Does this bug occur if you create the USB stick without persistence enabled? If not, then this could be fixed in Maverick and needs fixing in Lucid-updates, see https:/ /bugs.launchpad .net/ubuntu/ +source/ ubiquity/ +bug/627672