CRC errors mean the data being read is corrupted.
Are you burning CDs and verifying them, and that's when it happens or are you reading CDs?
If you are burning CDs, try reducing the burn speed or using good discs like Memorex or Imation. If you have trouble reading non burned discs as well, try the tips below:
Common problems in order from most common to least common:
Bad drive (or a dirty laser lens!)
Bad drive cable or loose connection
Bad RAM (use memtest86 to test the RAM)
Bad IDE controller driver
Bad IDE controller
Unstable or overloaded power supply (system may run fine until the disc drive is used!)
System temp too high (usually this causes much more than CRC errors
Is your system overclocked? Try reducing the over clock if it is. Bus overclocking causes this more than multiplyer overclocking.
If it turns out to be a bad drive, replace it with a Lite-ON drive. Cheap, reliable and fast drives, what more could you ask for? Get them at www.newegg.com