Sounds like the imaging hardware/software you are using is stripping all the security information from the clone. Normally, this is a good thing, except for the caveat that when you use the 'Welcome Screen' method for logging on, Windows XP does not display the Administrator account. With no other local accounts to display, you have no way of logging on! There are a few ways I can think to get around this.
1: Before you clone the master, disable the 'Use the Welcome Screen' option in the 'User Accounts' control panel (by selecting 'Change the way users log on or off'). This will enable you to use the local administrator account to log on to the cloned installation. I'd recommend running a utility that forces XP to regenerate an unique SID after booting from the clone. I used to run a utility called NewSID for Windows NT 4.0 systems. I'm sure there's a new one out for 2k/XP.
2: Before cloning, you could also disable the requirement to log on entirely by reading this article:
http://support.microsoft.com/default...;en-us;Q315231
You can also use TweakUI to do this, and there's also some obscure control panel applet that you can issue from the Run command (I forget what it is, though). Just remember to reinstate the requirement after everything is running properly.
3: You could use the Sysprep utility in the \support\tools directory of the Windows XP CD. Although it would be a good learning experience, it would be quite a bit of trouble since you would have to reconfigure both the master and the clone to some degree.
4: The cloning hardware/software may have the option to disable it's removal of SID information on the clone. Norton Ghost used to call the utility that performed this action 'SIDWalker'. Since I'm an IT outcast that hasn't been afforded the pleasure of deploying 2k/XP machines, I've been out of the loop. Therefore, a newer version of Ghost may be out that incorporated 'SIDWalker' as a simple option. Then again, you may be using an entirely different imaging solution. I used to deploy images using both Ghost and a hardware duplicator (whichever struck my fancy at the time).
I'm sure there's more. If I think of any, I'll edit this message. Good luck to ya. Of course, all this may be totally off the mark, but it *seems* logical.