Why won't Ubuntu load the login screen?

I'm trying to run ubuntu off of a flash drive but after the loading screen then it quickly goes to some silver screen then it goes to a black screen with just a cursor. After sitting here for about 5 minutes the cursor disappeared and it's just black. My PC is a Lenovo ThinkPad X200 Windows XP 32bit SP3.

Which version of Ubuntu? How much RAM does your PC have? You might try Xubuntu or Lubuntu, or go to the ubuntu.com forums for help.