Vista x64 upgrade to SP1 black screen with cursor

Hi all.

I recently upgraded my Vista x64 to SP1 it worked fine for a day or two and now bootsup successfully to a black screen with a mouse cursor.

No login screen and i cannot use Ctrl alt delete

I have tried the following :

I have tried every possible bootup option from the F8 menu (Yes safe mode does the same)

I have tried the windows repair cd and used the automatic repair it just says the system as booted up successfully (So it not a bootup problem)

While in the windows recovery
I used chkdsk /f , bootsect replace the MBR and also tried the BCDedit etc
I also manually replaced the software and system files under windows\system32\config with older versions that worked previously
When i tried to do a system restore from the Repair CD it says no restore points availabe which
is very weird because i had made one before i upgrade to SP1

I have tried regedit and made sure the winlogin shell is set to explorer

I know has a last resort to i can reinstall a clean copy but i would really like to save the OS if possible.

My specs
Asus striker II extreme (latest bios) MB
E6750 Cpu
4Gig 1600mhz Corsair ram
750GIG western Digital HDD
7800GTX 512mb
550watt Psu

Any help will be appreciated

Thanks in advance

Before reinstalling from scratch, I would at least try to reinstall over it.

I would also reset the BIOS (if was overclocked) and do a HDD/RAM test (not just a chkdsk /f).

Otherwise, a clean installation is advised.

It make sense to disable the installation (overwrite) while the OS is running. You must install from booting from the DVD and not do an installation from Windows.

Just put in the dvd and reboot, at the post, boot from the dvd and just do a normal installation without deleting your partition. It might not work but worth a try.