Having problems booting xubuntu after installation

view story

http://askubuntu.com – I'm newbie with ubuntu, I tried to install ubuntu, at the beginning xubuntu work for the first upgrade to xubuntu 12.04, but after the reboot, no winxp media center ether Xubuntu won't start and I have a screen Ctrl+Alt+Del nothing else. I read a little about, maybe the sata enabled on the bios. What is the problem and can it be fixed or do I have to remove xubuntu. Partition is : 100gb xubuntu 220gb winxp I have an external drive 1 tb Thanks for the help. (HowTos)