Have a look in the sysprep.inf and see if there is an autologon line. If there is, set it to no.
For the exact syntax in the [GuiUnattended] section, look in the ref.chm.
Tip: copy and paste for best results. Be sure to omit the spaces before and after the "=".
When I use sysprep it reboots right away. As you know I can't go back in and check the file without it ruining the sysprep operation. Is there anyway to see what the file says before reboot?