PC won't start after installing Windows Vista service Pack 2

I was minding my own business when Windows Update said I should install Vista Serivce Pack 2, so I did. The update seemed to install fine, then it said I should restart, so I did. Now my computer won't go past the boot screen. It's a blue screen that says HP Invent. My PC is an HP Pavilion Slimline. I tried manually shutting it off and trying again but it just WON'T move past the boot screen. I even tried going into safe mode by repeatedly pressing F8, or I tried pressing ESC to go into BOOT OPTIONS but it's like the keyboard isn't responding. I am on my laptop now. Does anyone know how to fix this issue?? Please!
Thanks.

 

I looked through the HP forum for stuck on HP Invent and you aren't the first person to have this problem.
http://h30434.www3.hp.com/psg/search?board_id=lockups&submitted=true&q=HP+Invent
Unfortunately, there doesn't seem to be a solution. Most threads don't offer a suggestion as to what you can try.

If I were you, I'd email HP support and see if they can offer a solution or give you a link to a web page with a solution.

 

Try to boot into safe mode by taping F8 on your keyboard until you get options select safe mode and uninstall Service pack 2

 

Is it possible to uninstall service pack 2?

 

Click the “Start button”, then click “Control Panel”. Click “Programs”.
Under “Programs and Features”, select “View installed updates”.
On the “Uninstall an update” page, click “Service Pack for Microsoft Windows (KB948465)”, then click “Uninstall”. Follow the instructions on your screen.

 

Try to hit F9 instead repeatedly this should take your to system diagnostics on Hp Computers check you hard drive for errors. If that Doesn't Fix the problem you should do a repair install using the manufacturer OEM CD becareful doing so and please fully read the instructions you want to keep your files so you can't do a complete format or you will loose everything here's how you do a repair install:
Mainly boot using the OEM and when the blue screen comes hit F8 : "I agree"
Then the system will look for previous OS installed " old partitions" then will either ask you to repair an existing system which you want to do you need to hit R if you hit ESC it will by pass that screen and to proceed you have to format the HDD and your old file will be saved in a folder named .old computer on the root. But if you hit R at the first Screen it will fix the current partition that was detected on the HDD. Basiclly it will rewrite your system files keeping your data intact. that should fix your boot problem unless you have a bad MBR.