Sounds like K3B and Brasero don't like burning from samba. Did you try mounting it?
Code:
mount -t cifs //yourshare yourmountpoint -o nounix,noperm,gid=users,iocharset=utf8
I found this that on an opensuse forum, and it worked fine on Slackware, but you may need to tweak some of those options, maybe use smbfs.
This should trick K3B into thinking your share is a real local folder. You could still run into problems if space is an issue on the burning computer, K3B caches to /tmp. I would also recommend to you burn at the slowest possible speed and use the 'verify written data' option to help avoid coasters.
Good luck!
