So when I start the game, HOMM3 doesn't seem to find my CD, even though I installed it from gog... How is this even possible? I can't play anything but multiplayer. Anyone know what the problem is? I've tried running as administrator and also in compatibility mode, and I never have installed HOMM3 from CD on this computer before. I do have HOMM3 on CD too, still working but it's not the complete edition, haven't tried that out yet but I doubt it works, and it shouldn't require that in the first place.

Thanks, that HD mod did the job.

I have the same problem, i buyd the game from another store but it says that the cd cannot be found and i only can play multiplayer, but do you guys have any links or downloads for Heroes of Might and Magic III HD Mod?

Here.

Allright, but however when the disk is inside the computer and you run the game, it works 100% you can play singleplayer too

I have the same issue. Here is what I've tried to resolve it:
1) Ran the game as administrator (as well as various compatibility modes)
2) Checked registry for old homm3 key (although I'm fairly certain I've never had it on this comp)
3) Downloaded and used Heroes3HD.exe.
*edit 4) Checked the registry value of CDDrive in registry, it was already set to C: (which is the correct hard drive)
Single player and campaign work with the HD mod, but the game is unplayable due to frequent crashes. I installed the HoMM3 HD 2.98f version. Any ideas?

You need to set affinity to a single CPU core. How to set affinity temporarily.
Permanent solution (using imagecfg).

That seemed to do the trick, thanks. Audio sounds a bit laggy, but otherwise runs perfectly.

I've found an easy way without installing the MOD, just run regedit, find "new world computing", under it there are two keys, one is called "Heroes of Might and Magic?III" , the other is 'Heros of Might and Magic (R) III", one contains the correct string value "CDDrive=C:", the other doesn't. So just create a string value called "CDDrive" in the other , and set its value to "C:", problem solved.

hi, but how do u run the HD mod in mac

You don't. Unless you can work something out in Boot Camp or whatever you use to run other games that don't have Mac support. Like Heroes III.