Video drivers lost/misconfigured after reboot

Hello,

I am having a problem running any DirectX application (game or app) on my
PC. When I try I get errors either stating that I don't have a graphics card
that supports it, that I must update my graphics card drivers or errors of
missing DirectX files (error varies based on the application). Even things
like simple DirectX demos fail to run.

If I uninstall and re-install the drivers for the video card (rebooting to
complete the installation) things will work fine until I reboot again. After
which I'm back to the same errors. So it seems like the configuration is
lost after I shut down.

I've installed the ATI reference drivers (8-4_vista64_dd_ccc_wdm_enu_61009)
on 64 Bit Vista SP1. I have an Intel Core 2 Duo 8400 and 4 GB of RAM on an
Asus P53 motherboard and a Gigabyte Radeon HD 3870.

Any ideas on why the drivers seem to go missing after a restart? There are
no errors listed in DxDiag or Device Manager so they seem to still be there,
but applications can't pick them up. Re-installing the applications or
DirectX has no affect. The only way I can get things working again is
re-installing the driver.

On a side note about 1/3 of the time I start Windows I get the prompt saying
Windows wasn't shut down properly, even though it was. This can pop up after
I shut down or restart. Could there be a connection?

Mark