12.10 USB installation hang

[Shinray]

I am new to Linux.

I am trying to install Ubuntu 12.10 (64 bit) from a USB stick. I downloaded the ISO, checked the MD5 hash, and created a USB as per http://www.ubuntu.com/download/help/...ick-on-windows

I am currently using the live environment. Everything seemed fine, so I started the installation procedure and went with the default settings (Windows 7 alongside Ubuntu) and created a partition about ~40gb in size.

It's been an hour or so and I am still on "Detecting File Systems..."

PC Specifications, if this helps:
CPU: AMD Phenom X3 8450
Mobo: Asus M2N68-LA Narra3 OEM
Memory: 2x4gb DDR2 unknown
GPU: Sapphire Radeon 5670 512mb
Windows 7 Ultimate x64

I probably should have partitioned the drive prior to attempting install.

What are my options?

Thanks in advance.

[Shinray]

Anyone? I really would appreciate some help, since Ubuntu won't let me shut down, so I can't boot this computer back into Windows. Also, I discovered that the "ubiquity" process is stuck at 100% cpu usage...the load keeps cycling between cores, so one core is always maxed out. It doesn't appear to be doing anything though...the log in the installer doesn't report any activity.

[johnycsf]

To log back into windows you will need to have a Windows CD boot from it and fix the master boot record!
Ubuntu installs GRUB and if you're not successful installing it, it will replace mbr with grub anyways.