mount usb with the wrong user

Hello I installed trinity on a PC running Ubuntu Lucid (I did not do the original installation so I am not sure if something went wrong) However when I connect in kde3 an usb device with a linux partion 2 things happen - the kde daemon pops up twice instead of only once - the device is mounted but the files belong to another user of this PC. This is very annoying because in order to copy I have to use sudo and then later the chown chgrp command. I looked up the fstab file in /etc but there I can't see the source of the problem. Uwe Brauer