No Scrollbar on XP Welcome Screen

On Windows XP SP3, I have 7 user accounts, yet there is no right-hand scrollbar.

The only way to access any of the lower accounts is through the arrow keys or if I turn off the welcome screen.

Help from any of you which works is appreciated since it is annoying. I'm not sure but maybe using Safe Mode to replace winlogon.exe will work.
I know how to do that. And that doesn't answer my question.

In fact, I have notice that it does appear on the Switch User menu but not when I logoff so this makes no sense either.