Maximum PC

Hey,
I have an industrial machine that runs WinXP in the background. Upon boot it loads the proprietary software and locks out all access to the desktop, My Computer, any other programs / files, etc. I can access the desktop by doing a Safe Boot yes, but I don’t want to do that. Not even CTRL / ALT / DEL works, it brings up a screen “Windows XP Embedded” and the standard items such as “TASK MANAGER” are greyed out, the only option is “CANCEL”.

I know it’s possible to do this as the machine manufacturer said it was, but didn’t want to tell me how.

Is there a way to access the desktop with a secret series of keystrokes? How about a program that loads upon boot that will allow me to access said desktop?