Please do not try to install grub on the windows partition. It's meant to be installed on the MBR or on a Linux partition. I'm not sure if it does any damage if you try, but it's possible.
When grub starts, and seems to freeze, are you able to type anything? If you can your on the command line. Also, try typing the letter 'c', and see if that effects anything.
Was grub installed with your linux distro, or are you doing it on your own? If you are doing it independantly, you need to set up a /boot/grub/menu.1st.
When you are logged into Linux, see if that file exists, if it does, post the output.
Also, make sure that the last time you installed grub was to the MBR.
Here is a big grub thread.