|If the screen stays black as the computer seemingly boots normally, especially to the point of hearing the Windows Logon music, it sounds like there is a connection problem with the monitor. In addition, many monitors will go to Power Save Mode if they don't detect a connection to the computer.|
I've never used Windows Cardspace, but it looks like you can disable its connection with other applications by going to Windows Control Panel > User Accounts > Windows Cardspace > Preferences > un-check: Enable accessibility applications
You could also try disabling the Windows Cardspace service.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.