Nvidia card not detected

Vaio VGN AR21S
Nvidia GeForce Go 7600 GT
chipset mobile Intel 945PM express
CPU Intel core2 Duo T7200 2GH 2MB
2MB DDRR2

I Have a Sony Vaio VGN AR21S laptop, Working perfectly but will not detect integrated Nvidia graphics.
Device manager only has standard VGA graphis adapter listed and it is not detected when I use the instal hardware option
When I load the drivers for the Nvidia they appear to load and it says needs restart to finish.
goes through bios and then stops, sitting with black screen, nothing works and have to power off.
Only way out is to boot from installation disk and do Windows repair, this (I think anyway) either removes the Nvidia and reinstalls the standard vga
or allows the VGA to start
I need to know if the integrated Graphics are knackered and if so, is it fixable? or is it something else?
Would appreciate any advice
Boyd

 

(may not be directly applicable since I have a different model, but perhaps this would help)

When I upgrade my video driver it will also end up with a black screen and I have to do hard power off. I usually wait for quite a while (at least 5 minutes) before I power off. But when I boot, I can choose normal procedure and it'll load okay.

 

Thanks for that, will give it a try over the weekend
Boyd

 

HI, I tried switching off and waited 30 mins and it made no difference
however I went on to sony download and checked for updates and there is a Beta driver for Nvidia that was not there previously, so in the hope that it was a W7 driver (Previously there were only Vista drivers) I downloaded and installed.
After restart it started to load Windows, no sign of the previous black screen, but about 30 seconds after it started to load I got the dreaded Blue Screen of Death. I could not read all of what it said as it switched off too quickly, the second paragraph said that there was a problem with the Nvidia graphics and it was switching off to protect the computer.
So, I am no wiser really.
I posted this answer earlier today bit I may have hit wrong button as it is not showing on the answers, on my screen anyway, so am trying again
Boyd

 

The 7xxx and 8xxx series graphics cards from nvidia were both prone to failure. It sounds like you may have one. I had a GeForce 7400GO do the EXACT same thing, and nothing will fix it short of baking it, and that's a very temporary fix.

 

That is what I am beginning to think myself, I think I will give up on it and sell it as faulty
So thanks to those that rtesponded
Boyd

 

Have you tried installing sony's specific drivers for your model? Stock Nvidia drivers will not work with most vaio's.

 

Sorry hadnt looked for a while and didn't answer last. Did download from Sony
Anyway decided it was graphics chip and was right
Computer shops talked telephone numbers, but I found a guy on ebay who fixes the Graphic chips on Sony Models (Apparently it is not the chip, but the solder) and sent it and had it reseated for £89 and works perfectly, anyone with the same problem you will find him if you do a search for your Sony model no on ebay and his is the one without a photo just the vaio logo. if you email him with your symptoms he will tell you if it is fixable, he has done 2 for me so I would recommend
Hope this helps anyone who has a similar fault
Boyd