This game is killing me. It's the first in the genre I really enjoy and it's not letting me play it due to it being a buggy piece of shit. I realize having researched the problems it has a reputation for this. Um. But yeah. I've tried everything, and both patches are installed, all latest drivers etc. Running XP.
I sometimes get the "memory could not be read" error. I sometimes get the "Internal driver error in IDirect3DDevice9::Present()" message. Both of these seem to occur most frequently (or exclusively) at the load screen for Stonehelm (between the prologue and Ch.1). And as of now it just doesn't want to start -- I tried lowering the resolution to a 16:9 one -- it crashed and now won't start..workarounds (like command variables) don't do anything.
So.
Does anyone have any advice or should I just give up on this game?

Crash problems are unfortunately very common in Dark Messiah. My desktop runs it relatively fine, but my laptop keep crashing every 10-15 minutes.
Try the basic remedies first. Turn down the graphics and special effects. Minimize background applications. Make sure your memory and harddrive are fault-free as this game moves A LOT of data back and forth.

Have you read the 3 Tech help sticky posts on the Steam forums?
http://forums.steampowered.com/forums/showthread.php?t=500984
http://forums.steampowered.com/forums/showthread.php?t=483994
http://forums.steampowered.com/forums/showthread.php?t=502212
I don't know if any of the information will help you, but it's a starting point if you haven't seen them before.

I couldn't finish the game because a damn crashing bug kept throwing me to the desktop at some point.

My machine is more than enough for it, except the RAM..I have 1GB as the other GB recently died..waiting on a replacement. That's still the recommended, though I know 2 is the "real" recommended. Still, doesn't explain why I can't start the game. =/
Anyway I did check out the Tweakguide on it and turned down the unnecessary settings..textures at medium..etc. I could lower them further but I don't think that's the cause of the Direct3D error.
Well, it's nice to see word from Arkane..
The third link's link is dead..but I did read this massive community thread. Nothing appears to work, really..
Yeah, I get lots of those, too.
I've reinstalled since, successfully changed the resolution to a 16:9 one and ran the game for a bit, but then it crashed at the same spot and since then I haven't been able to load it up again. It just does nothing at all..the SecuROM thingy shows up and then nothing..or a black screen then back to the desktop. =/
This is the worst case I've ever run into with a game..yarghh..
Appreciate the help, guys.

Argh, bad memories. This pissed me off so much. I never found a solution, and ended up having to rely on pure random chance, and eventually gave up on even that.
However, something - and I have no idea what - changed in my computer at some point between early 2008 and mid-2009, and in mid-2009 I was able to run it without a hitch. Thing is, I don't believe ANYTHING was changed. I can't think of a single upgrade or configuration that would've fixed the issue.
Are you playing the Steam version? Come to think of it, my second playthrough used that one, but the first was a retail copy - fully patched, though. And possibly cracked, too.

I never had any problems with the Steam version at all. Not with either nVidia or ATI cards either. Maybe the Steam version fixed something seriously wrong that went unpatched in the retail version?

Edit: I fixed it. :)
After doing some harder research, I discovered the game doesn't like to scale resolutions. So, though 16:10 resolutions aren't officially supported, I should use one anyway, unless I want to lower my monitor and game resolution and restart every time I want to play the game (no thanks).
To get it back to 1680x1050 I had to do it via the registry. For anyone stumbling upon this thread, this is how to do it:
[HKEY_CURRENT_USER\Software\Valve\Source\mm\Settings]
Double click ScreenHeight, click Decimal, and put in your height res, then do the same for ScreenWidth.
All done. :)
Still getting the Direct3D and memory errors, occasionally, though..seem to occur when an event of some kind is triggered, like a level loading or something in-game.

Anybody? :(
Edit: FIXED, thanks to some wonderful help. On 1GB of RAM at least, do the following:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
Double click "PagedPoolSize" and change the (hexadecimal) Value Data to 10000000.
Works 100% flawlessly now. :)