I had the exact same problem in 2.0 x64. It turned out to be the size of the pic used.
You need to go to Applications - System Tools - Ultamatix. If Ultimatix is not there, go here and download:
http://forumubuntusoftware.info/viewtop ... 28&p=32242 (3rd post has the .deb to the latest version)Double click the .deb to install.) Then go to Applications - System Tools - Ultamatix
Start it up and browse through until you see Start-Up Manager. Tick it so that it will install then let Ultinatix do it's stuff. Under System - Administration you will find a link to Startup Manager. Click it.
Under Boot Options is a Display section. Mine was 640x480 using 8bit. Change it if need be.
The other option is download and install 2.1 x64. The new version fixed my problem immediately ( the details above were set up on installation).
Hope this helps.
Cheers