Lock Up When Flushing Buffers

Any Suggestions?

Yep.

OS?
Burner brand & model?
Reader (if used) brand & model?
title to be backed up?
media used?
settings?
rig configuration?
version of CloneCD?

Have you read the links for Down & Dirty and Settings pinned as Sticky Posts?

What’s to be looked up when flushing buffer?