I/O Error decrypting Spiderman & Harry Potter

[Droppo]

trying to rip Spiderman and Harry Potter DVDs got the following error:

check this screenshoot
http://droppo.com.ar/cosas%20droppo/error%20DVDDecrypter.jpg

I 03:37:38 DVD Decrypter Version 3.1.7.0 started!
I 03:37:38 Microsoft Windows XP Professional (5.1, Build 2600 : Service Pack 1)
W 03:37:38 Drive C:\ (FAT32) does not support files > 4 GB
I 03:37:38 Initialising SPTI...
I 03:37:38 Searching for SCSI / ATAPI devices...
I 03:37:39 Found 1 CD-RW and 3 DVD-ROMs!
I 03:38:00 Operation Started!
I 03:38:00 Source Device: [1:1:0] SONY DVD-ROM DDU1621 S3.2 (G:)
I 03:38:00 Destination Folder: C:\DVD_VIDEO\VIDEO_TS\
I 03:38:00 Detect Mastering Errors: No
I 03:38:00 Fast Error Skip: No
I 03:38:00 File Splitting: By File
I 03:38:00 Multi Angle Processing: No
I 03:38:00 Remove Macrovision Protection: Yes
I 03:38:00 Stream Processing: No
I 03:38:01 Decrypting VTS_01_4.VOB... (LBA: 1800721 - 2325007) - KEY: D7 48 32 D5 81
E 03:41:42 Failed to read Sector 1891666 - Illegal Mode For This Track
E 03:41:42 Failed to decrypt VTS_01_4.VOB!
E 03:41:43 Operation Aborted! - Duration: 00:03:42
E 03:41:43 Average Read Rate: 819 KB/s (0.6x) - Maximum Read Rate: 9.981 KB/s (7.2x)

Any idea???

Droppo.-

[LIGHTNING UK!]

Looks like you've got a bad disc to me.
Check it for dirt/scratches. If none are visible, take it back and get it exchanged.

[Droppo]

Thnxs Man! It was scratched... :S

Droppo.-