[solved] Windows 7 failing to reinstall

[hitbyambulance]

I am having problems with my new video card (apparently did not fully uninstall the old video card drivers - dxdiag is still reporting the old video card - and among other issues i get "special memory pool allocation error" BSODs when restarting the machine) and am attempting to reinstall Windows 7, as nothing else I've tried has worked to fix this issue.

When I boot Windows 7 64-bit Ultimate edition from DVD or USB, I get the GUI installation background 'wallpaper' and mouse cursor, but no dialogs, nor is any sort of actionable input displayed. I have to press the reset or power button here to exit.

Attempting to set up from within Windows 7 will successfully copy and extract the installation files, but upon reboot, when the GUI installation screen is displayed with "Setup is starting...", the dialog "Windows could not start the installation process." immediately displays. I can only exit and reboot at this point.

I am attempting to again install from within Windows, but disabling MS Security Essentials first. (I do not see any sort of boot-sector protection options available in the BIOS.) If that fails, I would probably have to fully reformat the hard drive and hope that booting from DVD/USB will display the proper installation dialogs, but that seems a bit risky at this point. I could also attempt to install Linux and see if that fails miserably.

System specs:
8GB (4x2GB) A-DATA Gaming Series 240-Pin DDR3 SDRAM 1600 (running at 1333 speed)
AMD Phenom II X4 925 Deneb 2.8GHz Socket AM3 95W Quad-Core Processor
GIGABYTE GA-770TA-UD3 AMD 770 AM3
Socket AM3 PC3-10600 (DDR3-1333) ATX Motherboard Retail
HIS Radeon HD 5770 1GB GDDR5 PCI Express 2.0 x16
1.5TB Seagate Barracuda 7200 HD
SilverStone ST50F 500W PSU

I should note that MemTestx86+ and Windows Memory Checker (whatever that's called) do not display any errors in RAM.

Ideas?

[hitbyambulance]

looks like i posted too soon - disabling MS Security Essentials allowed the reinstall from within Windows to correctly finish. (... really?)  still doesn't explain why the booting from DVD/USB failed.