I would recommend this article named 'Disk cannot be read from or written to' when syncing iPod or 'Firmware update failure' error when updating or restoring iPod found here http://support.apple.com/kb/ht1207
Outdated operating system software
Make sure you have the latest updates for your operating system, which may include improvements for device connections. For example, many USB and FireWire improvements have been included in Windows Service Packs.Check for Mac OS X downloads. Check for Windows updates.
Computer needs updates
Make sure you have the latest updates available for your specific computer model (or components for home-built PCs). These are usually available for download on the support website for the maker of the PC (or component). Many USB updates are listed as "Intel chipset" or just "chipset" updates on PC manufacturer's support and download websites.
Some software can interfere with iTunes, making it unable to write files to your iPod. Think about what software you have installed, and try disabling any add-ons that might be interfering with iTunes. Check your suspected software's documentation or contact the software maker if you need assistance with disabling the application. Out-of-date or incorrectly configured security software frequently causes this issue. See these steps for identifying and troubleshooting third-party security software.
If one of your music files or photos is damaged, iTunes may display one of these errors when transferring that file to the iPod. If you identify a file that is causing the error, try deleting that file and reimporting it from a backup file or from the original source. You may be able to repair files by repairing the disk (see the solutions in the next section).
Unregistered .dll files (Windows)
Malware or other software may cause an issue with the digital signing of Windows XP drivers. First try restoringthe iPod using the latest version of iTunes.. If you are unable to restore it or the symptom reappears, follow the steps in this document.
Damaged disk structure
These errors can also appear if the format of your computer's hard drive or your iPod disk is damaged.
To repair your computer's hard disk—Mac OS X users, read this article for instructions. Windows users, search the Help system in Windows for chkdsk to get more information on checking and repairing the disk structure.
Warning: Be sure to back up your data before restoring an iPod. The restore process cannot be undone. All of your songs and files will be deleted.
Corrupt iPod photo Cache
If you're getting the error when transferring photos to an iPod photo, try deleting the iPod photo Cache and then starting the photo sync again.
Make sure that the connections from your computer to the iPod are snug and do not wiggle or come loose during transfers. For example, if you use the wrong size dock for your iPod, it can put strain on the connectors and cause a bad connection. See these articles for more information:
Conflict with third-party hardware
Third-party USB or FireWire devices may also interfere with iTunes' ability to communicate with your iPod. Remove all USB and FireWire devices except the keyboard and mouse before reconnecting your iPod to the computer.
Hardware failure or non-compliant hardware can cause these errors. This could be an issue with iPod hardware or with the cable or dock you're using, but more often it's an issue with the USB or FireWire card or interface in your computer. Some USB and FireWire interfaces just don't work very well. If you isolate the issue to the USB or FireWire interface in your computer, you may want to try a different port, get the computer serviced, or replace the card or interface with a better one.
If you isolate the issue to an Apple-supplied cable or dock, or the iPod itself, you can get it serviced here.