Trying to install ubuntu 10.10 with Windows 7

Hi, I am trying to dual boot Windows 7 Ultimate 64 Bit with Ubuntu 10.10 32 bit. I am doing this via a 16GB Micro Cruzer Sandisk pen drive with file persistence (4GB Casper). However, once I have chosen how I want to partition the drive and go to install Ubuntu it gets stuck in the section where you define you're user name and password. I'm not sure what could be causing this or how to go about fixing it. Any help that anyone can offer will be much appreciated. Thanks.