Won’t boot to login

I have XP Pro. Hard drive is partitioned into two with dual boot. When I start the PC – I select one partition called “Games” and it starts ok – no problems. If when I start the PC and select the other partition called “Windows” it goes through the process where you see the Windows splash screen (the one theat shows “XP” and the moving bar….) it finishes that but then does not go to the blue login screen – it goes to a blank black screen and all you can see is the white cursor.
Any help appreciated.