This is an error often associated with build 2600, the copy floating around the 'net. Not saying yours is, but I've come across it many times.
I have gotten around this by a simple reset and keeping everything the way it is, leave the CD in and everything the way it was. It will continue from where it left off and everything is ok.
Hope this helps,
Vikram
BTW - I've successfully done this both from a boot install and a inside OS clean install.