My compuper starts up as normal. It boots and shows the Windows XP-logo when loading. The problem occurs when I get to the screen where I can (or in my case could) log on with different users. The screen gets black instead of giving me the logon-screen. But I can move the white mouse pointer around the black screen. If I leave the computer for a while (about 3-5 minutes) it shows a error message which is something like this: "winlogon.exe - application error" and it mentions something about "referenced memory" "Press OK to terminate or cancel to debug". I can press OK or cancel, but neither helps me. I installed Windows XP SP2 a week ago. Could that be the reason leading to my problems? Yesterday I tried to upgrade my Windows-installation with a XP SP 2 installation CD. This helped me as i then could enter Windows as normal. Everything appeared as before. But when I started my computer today the same black screen appeared. Anyone got some tricks or solutions to this problem?