"Cyclic redundancy check"

What exactly causes this error?

"Cyclic redundancy check" is an error caused by the DVD-ROM Reader
having difficulty reading the DVD Original/Copy.
this error means that the DVD Reader is possibly "dirty."

True story: I had a computer with a DVD Burner by liteoN and a DVD writer
by Liteon as well. Copied DVDs fine for a couple of days then I ran into
the CRC Error "Cyclic redundancy check" I thought it was the DVD it self
the source disc. I replaced the DVD-ROM reader with an LG DVD-ROM reader
& CD burner and the "Cyclic redundancy check" problems went away like magic.

What I recommend is buying a reliable DVD-ROM Reader like LG DVD Reader/Writer
products.

What I recommend is LG products