What media are you using to do the update with? Make sure its a high quality one, say sandisk or something similar and its formatted with fat32.
Also what are you using to decompress the zip update file you downloaded? I would suggest 7zip, winzip or winrar.
You can also try doing a fresh format on the media, using the format tool under the right click menu on the drive icon for fat32 full format not quick one.
What its doing there is running a md5/crc or checksum on the files to make sure they are perfect, the last thing you would want is a corrupt file updating your unit. So be very happy it failed before it updated and not during!