A new alpha version of the mod is now available from the downloads section. We believe the cause of the crashes has been fixed in this version. I ran a test game as Germany last night and got to 1941 without a single crash before I called it quits, whereas in the previous version you couldn't get past 1938 or so. There may be late-game crashes we haven't found yet, because we were focused on fixing the early-game CTDs. Please note that you should delete any previous install of the mod, as this version is not save-game compatible with the previous TFH versions.
Other new content is the addition of the naval treaty capital ship construction limitations. The 5 treaty signatories will not be able to build CAs, CVLs, BCs, BBs, or CVs until they leave the naval treaties. They can research ship techs without restrictions. France is a special case, since it hadn't historically reached its ship limit and could increase its battleship count. France will be treated separately in a later version, but for now it has the same limits as the other 4.
Other small bug fixes were added to this version, but the main thing is that we couldn't reproduce the crashes during our tests up to 1942. A full changelog is provided in the readme file included in the download. The only known CTD we found is one that occurs if you try to view the strategic resource statistics table in the statistics tab.
The mod is still in an alpha state and we expect there to be bugs and possibly crashes. If you follow the install instructions to the letter then it will start up without any problems; I'm testing with the exact same download you guys will get and I follow the instructions I wrote down in the download section and can start up the mod with no problems, so if you're getting startup issues then go double-check the install instructions. Once the game starts though, there may be crashes and buggy AI behavior due to TFH changes to the AI system from the FTM expansion. If you get a crash or see the AI fall asleep or build/research something silly then PLEASE comment here, in the ModDB forum for the HPP (check out the forum link to the upper-right, next to images), or the mod's main forum (official page in the mod's profile to the right) telling us what happened. The more detail you can provide the faster we can fix the bug or crash.
For AI-related bugs, it would help tremendously if after you quit the game you would go to the folder Documents\Paradox Interactive\Hearts of Iron III\HPP\logs, open the file system.log in notepad or some other editor, and check the bottom of the file for errors. This file is deleted every time you start the game, so please look at it and report any errors at the bottom before you start the game up again if you saw the AI fall asleep. If you do see any errors please report them, because the errors will point us to the files we need to fix.
Also, please keep in mind that generating the map cache can take a long time and hog up a bunch of memory. If you have an older computer, you may want to go to Documents\Paradox Interactive\Hearts of Iron III\map and copy your vanilla cache folder to Documents\Paradox Interactive\Hearts of Iron III\HPP\map (make this folder if it doesn't exist). This will bypass the map cache generation. You'll lose out on the visual region changes (the thick black borders on the map), but nothing else.