For now I can not find anything wrong with this pack that can cause problems in 409 ...
I wonder if you do not have another mod that does the parasite.
[Edit]
Pack P-40 work fine in UP2.01 !
Landing gear failed also work very well.
Well I don't know what you mean by 'landing gear failed' but I am starting to troubleshoot the problem with a process of elimination type of strategy. I happen to have two drives that I can boot into. I have Windows XP 32-bit and a drive with Windows 7 64-bit and I can boot into either with a bios entry. I had been using mostly XP and that's what I have been using to play the game. Well, I just tried booting up in Windows 7 and playing the very same install of IL2 4.09/UP2.01 where I put the put the P-40 pack. Just to see what would happen. Very similar thing happens but I get a delayed CTD where game freezes for 30 seconds or so and won't respond and then it finally goes to the desktop to tell me that the game had a problem. No memory error message but I would think it's the same problem, just a less geeky message.
Next I'll try to take out all other mods out of the MODS folder except for the P-40 pack and see what happens. Then if that doesn't help, I'll try an old install of 4.09m and put the UP 2.01 over the top of it again and put the P-40 pack in and try. That is only if I can find all the UP 2.01 install files!! If I can't find those, is there any way to download Up 2.01 anymore??
I did notice that a few other people commented earlier in this thread that they had the same problem I am having. So I am not the only person having this trouble.