Hi everybody :)
I re-installed The Longest Journey today (and I'm sincerely regretting uninstalling it in first place) and, when I launched the game everything goes well until the cutscene ends and April (is this her name? I can't remember) finds herself in the other world. At the exact moment the cutscene should end and the game itself should beging, everything freezes and the game crashes with the message "The Longest Journey has stopped working".
I remember some time ago I managed to solve this problem, but I can't remember how. Can anybody please help me?

These are my system specs:

Laptop: Acer Aspire 7750G
CPU: IntelCore i-7-2670QM 2.2 GHz with turbo boost up to 3.1 GHz
GPUs: Intel HD Graphics 3000 and AMD Radeon HD 7670M 2GB VRAM with AMD Dynamic Switchable Graphics Technology
RAM: 8 GB DDR3
OS: Windows 7 64bit

The game crashes whether I set it to run on the Intel or on the AMD GPU.

You could try deactivating hardware acceleration:

Open preferences.ini file in the game's installation folder with any text editor.
Now change the value for
bool_UseHardware=1
to
bool_UseHardware=0

Save and run the game.

I already did, and it didn't work...

Maybe it's the two graphic processors. Try forcing the game to use explicitly one of them in your graphic card's control panel.

I did that too, and didn't work... however, I turned the visual themes off and it seems to work for now...

Good, thanks for the feedback.

This worked to fix the problem for me on a Windows 8.1 machine ...

If you are running the game on a PC with multiple cores, change the "target" in the launch shortcut to the following.

C:\Windows\System32\cmd.exe /C start /affinity 3 game.exe

(Obviously you need to make sure the paths are correct for your environment.)

This will tell the game to utilize only cores zero and one. Apparently, the game has issues with there being too many cores on modern machines. I tried using only one core and that was not sufficient. Two seems to do the trick.

I had HUGE problems with random crashes at nearly every cutscenes - not just the first one. Tried all manor of affinity and CPU settings, with almost no improvement. Tried running other apps to slow the system - still no significant improvement.

Then I noticed a pattern - some cutscenes would transition FINE the first time through, but if the game was saved and that same cutscene replayed - IT WOULD CRASH EVERY TIME.

This made me suspect that it might be something related to HD caching and the hard drives latency being too low = i.e. my modern PC with it's SSD and large ram cache was just TOO FAST, and this was creating some kind of a race condition where a process in the game was getting ahead of something else due to the HD data arriving too quickly, causing a crash.

TLJ just did not like my super fast SSD.

So I re-installed the game to a slow external drive - first an WD "elements" spinning drive - then later to an older known-to-be-slow USB thumb drive - and in both cases PROBLEM SOLVED - no more cutscene crashes whatsoever (except for the infamous "Police Station" crash - but thats a known issue).

Just to avoid confusion I am not talking about installing the game FROM an external drive - that won't do anything - I am talking about overriding the GOG installer settings to install the game TO an external drive so the game will run from, and load cutscenes from, the external drive.