Your CD from which you want to copy the data, is corrupted (It is probably a CD-R or CD-RW or a CD with scratches).
You can try CD recovery programs, like the one in the next link:http://www.oemailrecovery.com/cd_recovery.html
You can also try cleaning the disc of GENTLY with soap and warm water under the faucet...but GENTLY. There are tutorials online on how to clean the disc properly, would recommend taking a look at a few to get an idea of how you should go about doing it.
I do not recommend doing it the way I am doing it because i know how to handle them pretty well...but I normally wash the disc with warm water first (HOLDING THE EDGES OF THE DISC), then just put liquid soap on it and GENTLY brush the disc LIGHTLY with a pre-wet cotton ball to remove the oil from finger prints from the disc...then wash the soap off and with an extremely soft cotton cloth (dont use paper towels, tissue, or toilet paper [no matter how soft they say it is] as they WILL scratch it) I use CLEAN cotton towels (or if I happen to be by my air compressor...shoot a blast of air at it from about 2 foot distance while holding it tightly on the edges with my other hand)...then after doing so take a look at the disc reflections and see if you missed anything (and if you have to use the cotton cloth towel, blow the lint off the disc before using it)...and then try the disc.
Visit the UBCD Wiki: http://wiki.ultimatebootcd.com
Please check your UBCD
ISO MD5 Hash Sum
; May prevent issues later on by not having an exact copy.
Currently Working on Common Issues and Repair Tips
on the Wiki.