This article is from the CD-Recordable FAQ, by Andy McFadden (email@example.com) with numerous contributions by others.
Start with http://www.mrichter.com/cdr/primer/udf.htm to get an
understanding of what DirectCD is doing.
A popular way to screw up DirectCD's UDF handling is to remove the disc
without letting the software finish up. You can accomplish this by rebooting
while it's working, attempting to disable it by doing something other
than uninstalling it (see section (3-45)), or by turning off auto-insert
If you have DirectCD 2.x, you may be able to recover the data with the
included Scan Disc utility. CD-R Diagnostic (6-2-6) may also be able
to recover data.
Rule of thumb: don't delete data off your hard drive until the disc is
finalized and verified readable. Too many bad things can happen when
writing to a disc.