Detta löste problemet för mig!
Saxat från Apples diskussionsforum http://discussions.apple.com/thread.jspa?threadID=1850824&tstart=0
Well I talked to AppleCare who couldn't help and organised a call out... I ended up talking to the tech guy over the phone first and, although this did not totally fix the problem, it allowed some burning access:
1. Go to Users/*user*/Library/Preferences/ and trash "com.apple.finder.plist"
2. Restart using the install disk. (Can take a while)
3. Choose your language
4. Open "Disk Utility" from the "Utilities" menu
5. Select main drive and "Repair permissions"
6. Quit "Disk Utility"
7. Open "Reset Password" for the "Utilities" menu
8. Select the target hard drive and select the user account
9. Click "Reset Button" under "Reset Home Directory Permissions and ACLs"
10. When button says "Done" in grey, quit and restart.
Trying to burn through iDVD seems to recreate the problem so I have had to do the above a couple of times... let me know if this works for anyone else or if the errors keep occurring