I do that presently ( 'mount /dev/sdb1 /pd' where i have created folder /pd . It works well )but as you know only root can mount so copying & deleting files to USB is tedious.
Just put an entry in your /etc/fstab then anyone can mount it.
/dev/sdb1 /pd vfat defaults,user,noauto 0 0
The problem seems to be with whatever system you are using to automagically mount the device. I suggest you find out what that system is and investigate it. Perhaps some Ubuntu users will be able to help you (I dislike and don't use automounting for devices like usb sticks).
PS. After adding the fstab entry, anyone can mount with the following command