iPod shows Error code 1415 in itunes after attempted restore

Hi,

I have replaced the front and back housing on a fully working iPod 30gb video. After being put together, The trouble is when I try and restore, I get the ''Your iPod cannot be restored error code 1415. also sometimes when I try and restore it freezes the computer, till I remove it from the computer. I have tried everything, resetting the iPod, forcing it into disk mode etc etc to no avail. Help would be appreciated as this is for a customer ;-( and I have never had this before thanks