It may be because it was previously and Active Partition. I'd recommend trying out Acronis Disk Director Suite to work out that problem. Otherwise, I'm seeing a reformat of the whole drive in the future.
EDIT: If you boot up a "Live CD" of Ubuntu there is a really nice program that allows you to resize your partition without losing any data. I would try using that due to the fact that it is free.
EDIT: If you boot up a "Live CD" of Ubuntu there is a really nice program that allows you to resize your partition without losing any data. I would try using that due to the fact that it is free.