in the command line type su and gain root access then change things.
and you have root access.
or you could just log on as root and see if this is your problems. try pressing ctrl+alt then any f key from f2-f5 or 6. then logon as root. then type startx . actulaly that might not work 'cuz i think you can only open one x session. so try the switch user options under the menu on the btm left. then log on as root. just try k3b from root. or check out the fstab entry in /etc/ youll need to be root to modify it. heres how i would do it:
cp -v /etc/fstab /home/yourusername
open copy in it you fav text editor (i like kate)
then find /dev/cdrecorder or similar.
heres what my cd and dvd stuff looks like
/dev/cdrecorder /media/cdrecorder subfs fs=cdfss,ro,procuid,nosuid,nodev,exec,iocharset=utf8 0 0
/dev/dvd /media/dvd subfs fs=cdfss,ro,procuid,nosuid,nodev,exec,iocharset=utf8 0 0
i have no problems with that. dont ask me what it all means.
change it then save it.
then cp -v /home/yourusername/fstab /etc/
yeah thats it i hope. im pretty new to this too. no else seemed to be helping you so i thought i give it a shot. good luck.