Game Crashing

[Annoyed-As-Hell]

Hello.

First of all, let me say thank you in advance and apologize if this isn't the right forum in which to post.

I have a very annoying problem. I'll start from the beginning: two days ago, I decided to install Roller Coaster Tycoon 3 (Scholastic edition) because, well, I guess I just had the craving to be a tycoon. Anyways, when I first clicked the icon to play, AVG notified me of a Trojan Horse virus in the file. I was shocked, so I quickly hit "Heal," but the game executed anyways. I figured whatever had happened wasn't anything major, and so I went on my merry way and started building a sandbox park. However, the game crashed after a short while. Now, that was yesterday, so I may be mistaken here, but I believe it simply crashed to the desktop. Anyways, I went back into the game, lowered the graphics setting (which the game had automatically set to "Extreme" based on my graphics card, a Radeon X1900 GT), then started building another sandbox. It crashed again. I researched the problem online and concluded that my audio and video drivers were out of date. Admittedly, I hadn't updated them since I first got the computer (two years ago), although they had been working fine for all of my other computer games. Accordingly, I went and downloaded the latest driver package from ATI (72 MB). I hoped that would solve the problem, but it got much worse. When I clicked the RCT3 icon (after having restarted the computer for the new driver), I got the same notification from AVG. This time, I didn't click "heal" fast enough. The game opened, I minimized it, then thought about this notification. I concluded that it must be an overreaction, considering the causal relationship between it and playing the game. My thinking was (since I know this to be a valid copy of the game), Atari wouldn't include a malicious virus in their software - that would be incalculably stupid legally. So, I hit "Ignore." I played the game, even lowering the graphics further so as to err on the side of caution. This first time it crashed to the desktop and I got an ATI error report saying the card had stopped responding and was reset. Then, I tried again, perhaps stupidly, but I wanted to check. It lasted a good, long time this time. Again, however, it crashed. This time, the game freaked out and signal to my monitor died. (All the cables are properly in place.) Needless to say, there was nothing I could do in this blind state, so I committed the most emphatically awful offense known to computer-users: I took out the CD and manually turned off the computer. I restarted it after a little while, and it appeared to work fine...then the wallpaper vanished. Oh, bloody Hell. Knowing this to be indicative of a virus, I then ran both AVG and Spybot, Search and Destroy to virus-check. They came up with nothing relating to this issue. I decided to get a third opinion, from Malwarebytes. It caught a few things, I healed them, and then reset the wallpaper. It seemed to take. Then I remembered I had only upgraded the video drivers, not the audio drivers. So, I updated them. I restarted the computer, and the wallpaper again vanished. I tried again to play the game (this time I hit "Heal" for the virus prompt), but it again crashed with the same signal-wrenching effect as before. I've even tried playing other games (namely, Battle for Middle Earth II, which had previously worked very well), and the response was the same as it had been for RCT3. I don't dare try that again.

Can you help me?

My thoughts are that there's ether something wrong with the graphics card, the drivers I installed were installed incorrectly, or were, perhaps, corrupted, or that I have a nasty little virus hiding somewhere all three of my virus checkers cannot find it. Perhaps the graphics card has gone bad, but it seems like the timing is a little too coincidental. I've even found a method by which to revert the drivers to their previous states, but I lack the technical knowledge to actually effect such a change. (I'm not actually trained in computer use: I'm technically a novice.)


Specs:
(I know these to be correct, as I even checked using the DXDIAG tool.)
Operating System: Windows XP Professional (5.1, Build 2600)
Processor: Intel Pentium CPU 2.66 GHz (2 CPU's)
Graphics Card: ATI Radeon X1900 GT
Audio: RealTek HD audio output

Being fifteen, I tend to be an idiot sometimes, so, if I've done anything inexcusably stupid, feel free to point it out.

I thank you again for any replies this gathers.

[5NIPER_WOLF]

Hello and welcome to TSF.

I must say, when you originally clicked 'heal' for the virus message, that could have done damage, as AVG could have deleted a critical file.
There is nothing wrong with manually shutting down the computer.

Now, please tell us what your PSU Make, Model, and Wattage is. I would also like you to try running the game in compatibility mode for anything.
Try taking out your video card, and make sure you are running the integrated graphics chip (should be Intel Graphics Media Accelerator [ GMA]) and running the game, this will factor in the fact that the video card could have something wrong with it.
Also, try uninstalling the game using Revo Uninstaller and after reinstalling the game, disable your AVG or add the game to the exception list.

Ensure you have XP Service Pack 3 installed, run Windows Update to find any and all updates you might have missed.