This article is from the CD-Recordable FAQ, by Andy McFadden (email@example.com) with numerous contributions by others.
This is rare but not unheard-of. Spinning an object at high speed puts
it under a lot of strain. Poorly-balanced discs can cause vibrations and
make the problem worse.
Drives rated at 52x typically spin somewhere between 10,000 and 12,000 RPM
(see section (5-22) to see how this is calculated). This is not enough to
shatter a disc in good condition, but more than enough to destroy a disc
with minor defects. This is one reason why Sony's 52x drives default to 40x
maximum, with a "turbo boost" feature that enables 52x reading and writing.
Super-fast drives, e.g. 72x, are actually spinning more slowly, but employ
multiple read lasers to read from more than one area of the disc at a time.
http://www.rm.com/safety/ has some warnings and safety advice. There is
a PDF document http://www.rm.com/safety/Downloads/StructuralIntegrity.pdf
containing a thorough analysis of the problem. The study concluded that
uncracked discs are not expected to shatter in 40x and 52x drives, but
discs with small cracks near the hub of the disc are at risk.
If you have a disc with a visible crack in it, DO NOT use it in your
CD-ROM drive unless you can reduce the speed to 8x or below (the slower
the better). Not all drives can be slowed. For Plextor models use the
tools that came with the drive; for some models there are speed-reduction
applications available on the web; for others you're simply out of luck.
Nero DriveSpeed (http://www.cdspeed2000.com/go.php3?link=nerodrivespeed.html)
will work for many drives.
Some web pages with destructive experiments:
An episode of the Discovery Channel's "Mythbusters" TV show demonstrated
discs flying apart near 30,000 RPM. This speed would only be necessary for
a 150x drive. Apparently they assumed that 52x drives read at 52x across
the entire disc, rather than just at the outside where the amount of data
read per revolution is higher.