When it does that have you alt tabbed to look at the error box?

f alt tab doesnt work you can also look at the event viewer. Just type event viewer in the search box on your programs menu and the crash will be listed in there. Double click the crash and at the bottom it tells you what happened.

Also as a side note have you disabled your AV and firewall program, could be that stopping the program from what it is supposed to be doing.

I already posted screen shots of what my problem looks like.

It's an ingame error message, and it's blocked out by the greyed screen. The only reason I can quit the game without control+alt+deleting is because I discovered the 'Done' button by complete accident.

Yeah, but if you alt tab you may be able to see the error box, just keep hold of the alt key when you can see it (if you can) so you can note it down

Good idea. I just gave it a try but it didn't work. Thanks for the suggestion I feel bad I didn't think of that already.

Have a look at the event viewer then, mentioned it in an above post with an edit

Many thanks.

To recap things what we have tried today so we do not need to do it again:
1. Ensured that the latest supported driver is installed.
2. Ensured that the latest supported Direct X run time is installed.
3. Turning off Catalyst A I to ensure that is not stopping the game from running.
4. Changing Windows screen resolution down to 800 x 600 @ 32bit.
5. Running IWD with and without Open GL 3D support.
6. Replacing the ini files with ones that iainmet provided.

Other things that have been tried before in both threads for the sake of completeness:
1. Running the game in Windowed mode.
2. With 16bit colour.
3. Running as administrator.
4. Installing in various locations like C: or C:\Program Files (x86).
5. We have ruled out SLI and Cross fire as there is only one card installed / active.
6. Running GOG version and version from original CDs.
7. The range of compatibility options that can be set when right clicking on a short cut or exe.
8. And the age old turning off anti virus scanner temporarily (if applicable) .
9. Getting rid of frame rate counter.
10. *Edit* Various combinations of patches / mod / expansions.

I've attempted to play with my firewall and anti virus off/on. They didn't seem to have an effect.

Yes Nullzero, that is a good list.

Another thing I'd like to mention is that thanks to the access of the CD's and digital version, I've managed to test out :
-Original game
-Patched original game
-Original game with expansion
-Original game with patched expansion
-etc (Any combination mixed within)

(Yeah I'm desperate)

Coffee has led me to the Windows Registry.

Changing the Windows registry incorrectly can lead to having to reinstall Windows and all required programs, a look but do not touch policy is probably the best to start with.

So with some hesitation, I have attached a screen print of what IWD look like in my install of IWD. Please could you run regedit.exe from the start menu and then click on each [+] that is shown as a [-] on my screen print and then single left click on 'GOGICEWINDDALE1'.

Does your look the same (apart from the install date and location)?

I don't get this, I can't find it. I have it installed in the same place you have, and I trippled checked in my stardard directory and I can't see it in regedit.exe. I've gone back and forth, I've even just finished reinstalling it and it's not showing up there.

Edit : Assuming I never altered the installation (I didn't) is there any chance that there would be a discrepancy between yours and mine?

I agree, chances are incredibly small that they would differ in this case.

Is this the GOG version you've reinstalled? The GOG* keys obviously won't show up for the retail version.

Beyond that, the location of the reg keys won't differ just because you installed the game elsewhere, their values would but not their location.

I own 2 copies of the game AND the digital from this site.

Yeah, I know, I was just making sure it was the right one you reinstalled.

To recap things what we have tried today (08/09/2012 DD/MM/YYYY) so we do not need to do it again:
1. Ensured that the latest supported driver is installed.
2. Ensured that the latest supported Direct X run time is installed.
3. Turning off Catalyst A I to ensure that is not stopping the game from running.
4. Changing Windows screen resolution down to 800 x 600 @ 32bit.
5. Running IWD with and without Open GL 3D support.
6. Replacing the ini files with ones that iainmet provided.
7. Looking into the registry.
8. Using different keyboard short cuts to view errors (iainmet).

Other things that have been tried before in both threads for the sake of completeness:
1. Running the game in Windowed mode.
2. With 16bit colour.
3. Running as administrator.
4. Installing in various locations like C: or C:\Program Files (x86).
5. We have ruled out SLI and Cross fire as there is only one card installed / active.
6. Running GOG version and version from original CDs.
7. The range of compatibility options that can be set when right clicking on a short cut or exe.
8. And the age old turning off anti virus scanner temporarily (if applicable) .
9. Getting rid of frame rate counter.
10. *Edit* Various combinations of patches / mod / expansions.

Outstanding investigation:
1. tburger noted that he may try a installation on Linux in Virtual box to run the game.
2. iainmet suggested that the Windows Event viewer maybe a good place to look at errors that cannot be displayed on screen.
3. Miaghstir hints that further registry investigation maybe required.
4. ShadowWulfe recommends disabling extra screen if more than one monitor is plugged in.
5. Nullzero: Is Windows Vista fully up to date with all Windows updates installed including the service packs?

Currently rejected suggestions:
1. Using Windows 7 instead (ShadowWulfe notes that it works on his install of Vista).

Further information so the whole thread does not need to be read:
CPU: Intel Core 2 Q6600
GFX: ATI Radeon HD 4870
GFX Driver: 12.6 (latest available for above card)
OS: Windows Vista 64bit

I will be back on Sunday or Monday, but I leave you with the above recap and hopefully other people will be able to provide additional assistance.