BSODs are caused by driver failures.

So what we need to do is first of all make the BSOD hang around for a bit, so you can get the info you need, in order to find out what driver is failing.

So go to your System Properties - Advanced - Startup and Recovery Settings and uncheck Automatically Restart. This will make the BSOD stay on the screen until you press a key.

Several lines down, you'll see the driver that failed. It might be something like nv4disp.sys, if you're an Nvidia person.

Basically, you just need to update that driver, because whatever bug in it that's causing the BSOD has most likely been fixed in a recent update.

If updating the driver doesn't do it, then there's another problem and I'm sure if you're BSODding, you're not the only one.

Even if you do get HOMM4 working, I'm afraid you probably have wasted $10. It is, quite frankly, awful (coming from someone who grew up playing HOMM with his dad). But that's straying far from the point, let's get that BSOD fixed.

So recap:
Prevent auto reboot
Cause the BSOD
Check .sys file
Update driver .sys file belongs to
Try to run HOMM4 again
Realise the mistake of your purchase (either by playing it or by continuing to get a BSOD)

Disclaimer: Please disregard all of my biased claims against the validity and quality of HOMM4.

I saw no .sys file in the BSOD.

The file it referenced was cdd.dll

any idea what that is?

I'm having the same problem and have searched everywhere to fix it. I have so far havent been able to find anything. I bought the game and cant play it at all

Works fine on Vista 32 bit. Definitely slowdowns on some maps for some odd reason, but more than playable.

The BSOD issue in Vista 64 bit was supposedly resolved by installing Service Pack 1. It worked perfectly for me after that.

I have all of the latest updates for Vista 64 bit. It still goes to the BSOD.

At this point I've resigned myself to the fact that I wasted money.

I realize this is very late, but MAKE SURE you actually install the Vista 64 Service Pack (you probably will have to go to the Microsoft website to get it) and the optional compatibility updates through WIndows Update as well. Once you have all of those, the game should work (it fixed it for me anyways).

I just bought this game during the 50% off strategy weekend. I have to say I'm incredibly disappointed in GOG for claiming that it works on Windows Vista without fixing this problem, since I already owned the game but wanted a copy that would work on my system with no problems. (Really, GOG, So. Disappointed.)

That said, if anyone's still interested, I did manage to get it working fine on my system by using a VMWare virtual machine with my old copy of Windows XP on it. For anyone else -like me- who didn't find any of the service packs to help, that's a pretty reliable option.