Blank screen

Hello,
so yeah... everytime i start up windows right before it gets to the logon screen the screen turns black and u can still see the cursor, but nothing else and it stays like that for 3-5 min before going on to the logon screen. also, i dont know if this helps but i installed a custom logon screen for my comp but never did figure how to get it back to the default =/ what should i do? help is appreciated =D

OP: Windows XP professional (5.1, Build 2600) Service Pack 2Configuration: Windows XP
Internet Explorer 7.0