No Hard Disk Is Detected!

[Yoli]

So the title is the error message I'm getting. Right /now/, it's not actually a problem. It was a problem recently though, so still seeing the message worries me.

What happened is I got a new PC about a month ago. It was working just fine for 3 weeks or so, and then one morning (the morning I had to e-mail a final exam, ironically...) this message showed up and the PC wouldn't start or get into windows 7.

I took the thing in to see some computer people. They ran some diagnostics and virus scans and stuff, but it was clean, and ultimately they "fixed" it by reinstalling windows. So now, I'm still getting this error message but windows is loading (for the time being, at least). I'm also suspicious because I'm getting little crashes with it now. There have only been two so far, but I just got it back. Once the screen just "turned off", and the second time the screen was fine, but I couldn't input anything.

I'm seeing a D: drive with nothing on it under my computer, which is the drive/letter of my old HDD (windows itself was and again is on C:, which is an SSD). I'm also seeing a new drive icon now, which works just fine and has everything my old HDD had on it. When I double click on D: it says it needs to be formatted or has been corrupted or something... I don't want to mess with it much at the moment, but its weird seeing a "ghost" drive.

Some other forums had sort of similar issues. Some people got messages like this with an Asus motherboard (which I have too), and people thought they might need to disable IDE ports on stuff? I have no clue what that is, or if its safe to do without further ruining things. I also have no clue why my PC would have worked just fine for 3 weeks, and then suddenly stopped.

Any thoughts from the people here?

Edit:
One other thing that's probably important but I forgot to mention. Before it broke down on me, I got one error message about how overclocking had failed (it was awhile ago, and I don't remember the exact words). It struck me as odd, because I hadn't overclocked my pc at any point and I never told the people who put it together to OC it either.

[Yoli]

I've been looking around some more at various forums. It looks like people have had problems with their ATI 5970's causing crashes (although not necesarily like the ones I've had... but there's some stuff suggesting it might be similar). Some people said that it stopped happening for them when they started using old ATI drivers (10.3) instead of 10.6 / 10.7.

Anyone here have a 5970 and a problem vaguely like mine? Anyone here have a 5970 and decided to use an older set of drivers?

I don't really know what to do. It seems like I'm asking for trouble to roll back drivers and tinker with the pc when it's working, for the moment, but I have this feeling that it's going to crash on me again if I don't do something. And clean installing the OS and everything is a pain.