Hi... I managed to get around this problem.
Anyone else experiencing this... use another live-cd like Partition Magic to create some dummy partitions. I just plopped three ext2 partitions on the drive.
I guess that Ubiquity wants/expects to see a disk with existing partitions on it. And originally I was trying to install BT5R2 on a blank disk.
So... make dummy partitions. Then reboot and installation should be ok.