If you're refering to it just sitting with a Penguin on the screen, this happened to me with my 750. To begin with I chose to change the root partition size to 50Mb, then 57Mb, neither worked, then I tried 40 (I think!) and then it worked.
Strangely enough it wouldn't actually bring up the login prompt (the penguin was there the whole time) until I unplugged the power supply.
Si
