XP StartUp

When booting, things seem to be fine until the screen ask to you to click on the name of the user. Problem is the mouse will not function -locked up I guess. I have tried several mouse (mice) that work on other computers but I get the same results. Therefore I cannot start windows XP. I have a boot disk but it also freezes at the same point. I prefer to not reload Windows XP if at all possible. I need your help please – Thanks