HELP Dell Vostro 200

[Computernerd22]

I have Dell Vostro 200 and I added 1GB of RAM & another stick of RAM 2GB made by Kingston. Anyways, I installed it the system. I notice a big performance increase it was running a lot faster because it had 3 more GB of RAM in it. I updated AVG (I use the free version) then I ran AVG and 'scan whole computer' option.

I fell asleep around 400,000 already scanned. I wake up this morning look at the system the sreen is off but powered on and also I couldn't get the system out of it's mode. So I did a "hard shutdown" and now when I bring it up, it say, run windows repair or something similar to that. Now it just displays a black screen says /8,000 (something around there) and now I cant even get to the desktop or see the windows screen.

When I installed the 3GB of RAM I powered it on, it started right up with no problems, no errors it was running great. Now, this morning after I turned it back on it displays a "recent hardware or software changed could have caused this issue". Screen There are two options available:

(repair windows and run a diagnostics on it then the screen switches to black mode does a file scan then the system then the screen goes blank. I select the other option start windows normally same issue, here is what is displayed on the screen while it is scanning but spends 95% of it's time on !!

"0xc01a001d does a scan of23.578/87338 (\registry\machine\COMPONENTS\DerivedData)*"

then it goes to a black screen again. I already took out the RAM but having same issue. I never had any issues with the PC before. Need help, please.

I am unable to back up my system and this is my main system. I need to back up school work, papers, and pictures,videos, music etc...

All help is greatly appreciated.