sorry, I should have put all that in my first post, I wasn't thinking.
Yes I have a dual boot. Two seperate HDD's (Master is fine, Slave having problems), both with Windows XP (Master - Home, Slave - Pro), can boot from both.
When the Bios is loading I can select:
"Microsoft Windows XP Home Edition"
"Microsoft Windows XP Professional"
(I don't know if that's EXACTLY how they're displayed, but yes I have the choice of which boot sector I want to use)
I press the down key and select "Microsoft Windows XP Professional" (Slave HDD). The screen then goes to the black Windows loading screen that displays the "Microsoft Windows XP Professional" picture, and the loading bar at the bottom.
That page goes away and the blue "Log In" screen starts to load. It then freezes, or doesn't finish loading. All I get is the "Microsoft Windows XP" picture that is always there when you get the log in screen. No user names load, the shut off button in the bottom left doesn't load, the usual words "To begin click your user name" doesn't load. I only get that picture and the usual blue screen.
I have tried to boot in other options. Safemode, debug mode, system repair mode (not sure if that's what it's called) and last known good configuration. None of them will finish loading the usernames for me to log into.
Thanks for the help so far