I feel it's important to list here the most important remarks and rules to follow in order to get WW1 running fine:
1) WW1 Configurator tool: do not check the "Lock full-screen mode" option, unless you have no antivirus and/or firewall program installed on your PC.
2) WW1 Configurator tool: if you want to have a less jerky behaviour of the game during AI job, set the "Security Level" to 2. Thus you will be informed immediately about AI job by the usual black window inside the center of the screen. Remember also that AI can be paused/unpaused with the 'pause' key.
3) WW1 Configurator tool: Do not set the "Security Level" to 1. This could increase the risks of CTDs.
4) Scenarios: 4-players Grand Campaign 1914 has been factored for multiplayer sessions, not for single player mode. So, playing in single player, could generate CTDs, that are going to be fixed. In addition, consider that it's much nicer to play on the side of the Central Powers or of the Allies, rather than on the side of a single nation!

5) Options window: the "Give AI full time" option makes the AI calculation time very long, so avoid this option!

6) Patches: each patch will overwrite the WW1.ini file (where the serial key is stored). So, every time a new patch will be released, you will be asked to type again the serial key. I'll study a solution for this problem, of course.
Thanks for your patience,
Calvinus.