Can you give us your exact Hardware specs?
Have you updated your Drivers?
I have an Intel Core 2 Quad CPU Q6600 with onboard GPU @2.40Ghz
2.00 GB RAM
NVIDIA Radeon GeForce GTS 450 1GB
450W Power supply
Before I bought this card and new Power supply in March I used a very crappy 256MB cheap GFX card and 150W that came with the rig. Unfortunately this sucky card melted while I tried to run UP 2.01 in Perfect mode. After 2 years of normal and 6 months of abusive (perfect) use this card was crap. Blue-Screens/Fatal errors. I have made my experience, with a crappy card you can run, but it won't be fun. It was my fault, no doubt. After the card was over, I couldn't use IL-2, as my onboard GPU was too weak.
Age of Empires 2 was the only thing I could use, with stuttering. I got another borrowed card, which I suppose was crappy, from a friend, I couldn't run stock IL-2 and got Blue-Screens/Fatal Errors?! Then I knew I need to buy sth. new!!!
If you get Blue-Screens, my honest advise, leave this rig and update your hardware.
Even with this card I don't misuse anymore, I screwed the gfx down, to a mid level, slightly high Textures (in Conf.ini).
As DBW and UP3 are hardware hungry, even my rig is not capable of perfect. It can run this, but I would experience high stuttering, flickering, random CTDs. I could reinstall in that state every 2 days from scratch, just to realize the next Mod can break it again.
What you can do with your rig is install 4.010m IL-2 and play around with Conf.ini to see where's the max. your rig can hold, to get an affordable mid. range settings, where you can play at least stock IL-2. If you can't buy new hardware and wanna play you need to go through this anyway. Testing out your rig, getting a sense for your install, this avoids you to overshoot.
If it's strutter free, you have luck, all commands response in time? No delay, lag? See yourself on my post below, if you try to overload it will be your harm.
If that works flawlessy try the SAS Modactivator. Then again, it needs further testing how many Mods it can hold, a CTD indicates it may be over.
I would say it can't hold DBW or UP3, maybe on very low settings, but then I would prefer mid range at least on stock and only a few Mods (no 2 GB bloated Modinstalls!!!) of course.
Modded IL-2 can be very hardware unfriendly, huge Skinfolder, Gb's of Mods, FX, Sounds etc.