Stuck at "Installation Type" screen while installing

I'm installing Ubuntu from a USB, onto a computer running Windows 7. Everything seems to run perfectly, until I get to the "Installation Type" screen.

Essentially, I am not getting a choice for my install. I am taken directly to the partitioning screen. It has options like "New Partition Table...", "Add...", "Change..." etcetera, as well as a drop-down menu "Device for boot loader installation:".

Anyhow, nothing responds on this screen (but the computer does not seem frozen). From the Ubuntu website screenshots, this should be pretty straightforward!

What do I need to do to get Ubuntu installed?

My 13.10 install got stuck at a previous screen, asking if i wanted to replace windows, do something else, etc. The 'continue' button wouldn't enable. I clicked back, then next, and it cleared the problem. you probably already tried that?

Make sure your disk is readable. In my case AHCI was not set in the bios.

You can boot the usb in Try Ubuntu mode, then run terminal. Next try fdisk -1 or parted -l.

If your harddrive isn't in the list then make sure its bios settings are correct.

Make sure you do not have a bootguard, e.g., Symantec PGP, as it does not allow dual boot and you may end up losing your data.