Note - This solution appears not to work with cdrkit.
At times you might get SCSI errors when writing to DVDs (cmd timeout after 0.2xx seconds), sg_write issues etc... Just add -immed flag to cdrecord to fix the issue. Set k3b to use immed by default. This issue might be more frequent when using a DVD writer though a PATA to USB connector.
If you get misc. errors in general, then check if the priority of the burning program/backend has been manually set to high, this causes problems.