Installed graphics driver not working even though the computer says it does

I'm fixing a Pavilion DV7 for this guy and I'm having big problems with the graphics driver.

This computer has the M880G with Mobility Radeon HD 4250 and the Mobility Radeon HD 5470.

When I disable the 4250 and keep the 5470 on, the computer will start like it should, but if I try to run them both on enabled the screen will turn black right before login. I can hear the sound and everything, so it's not the computer crashing or anything like that. If I disable the 5470 the same thing happens. The only way the computer will turn on the way it should is if the 4250 is disabled while the 5470 is enabled. So I do get a picture, the computer itself is working, no problem there.

Safe mode works like it should and when the screen goes black I have to use the safe mode to disable the 4250 (and keep the 5470 enabled) to be able to turn the computer back on in normal mode. It's strange though that the computer says that the drivers are working like they should in the device manager, but they're obviously not; when scrolling the picture will lag pretty bad, and even though I've tried probably 10-12 different drivers (new ones, older ones, all kinds), nothing new happens to the computer when I install a driver. It's like the driver isn't "connected" to the hardware like it should, I have no other way to describe it. It installs the driver with the damn Catalyst piece of crap program and tells me everything is working...but no.

I've tried all I could think of - many different drivers, removed the old one and installed the new one instead, installed directx, framework, tried different fixes for scroll lag (which is pointless since this gotta be a driver problem)...I'm all out of ideas.

All suggestions are welcome, since I've tried just about every solution I could find when I googled. And feel free to ask questions - I think I put all the info I have in here, but if something is missing just ask.

 

But the computer do have two cards(?) (It's a HP DV7 4010SO)

It boots with the vgasave driver, and I can just as well disable both cards that shows up in the device manager; it will still boot the same way it does now and the computer will work. It says that the 5470 card works, but that doesn't matter since the computer wants to boot with the 4250, and the latter isn't working like it should and that is what causing the vgasave. I tried forcing the computer to use the 5470 all the time using CCC, but that didn't work either; seems like there are a lot of buttons that are not showing up in my CCC and that is probably because the 4250 driver isn't working. The computer doesn't recognize any of the cards.

It's not a clean install, the computer have probably never been formatted. I tried installing new chipset drivers as well but that didn't help. ATI drivers didn't work either.

The only yellow mark that is there is next to the 4250. If I uninstall it the computer will install the drivers by itself and when I reboot I get a black screen after the splash screen. I have also installed a number of other drivers for the 4250, but when ever the computer is telling me the 4250 is working I will get a black screen when rebooting. The 4250 _must_ be disabled for the computer to turn on. Weird, since I end up using vgasave drivers anyway. Hardware failure, perhaps?