Sometimes Windows XP gives you the following message in the system tray: "Windows needs your current credentials....
Please lock this computer, then unlock it using your most recent password or smart card. Please click the icon to see more information."
This appears to be a random bug in Windows XP, but here's a quick fix you can apply.
- Click Start, Run and type GPEDIT.MSC.
- Under computer configuration, expand administrative templatessystemlogon.
- Select the "Always wait for the network at computer startup" value.
- The default state is "not configured." Set this to "On."