Try flashing it manual without using the toolkit.
First you would need an adb and fastboot setup
Open the rom (.zip file) you downloaded and put the ''boot.img'' file in ''C:\android-tools''.
Make a nandroid backup
Full wipe(except sd)
Select reboot into fastboot
Flash the boot.img manual by :
- Go to start->run-> type cmd and press enter. A command prompt will now appear.
cd c:\android-tools [press enter]
fastboot flash boot boot.img [press enter]
Do make sure you're in fastboot and not the other.
After it's successfully installed, turn of your phone and just boot normally. It may take a while for your phone to boot up.