It probably works because your AppPool is likely set to 32 bit in which case it works fine. If the app pool is set to 64 bit though I'm pretty sure the CDO/ADO stuff will start to fail.

Either way... just make sure the app runs in 32 bit mode.

+++ Rick ---

>>The .NET 4.0 and 4.5 install packages should contain both 64 and 32 bits in the same package. If you're unsure use the Web installer and it will install what's not already on the machine...
>>
>>I would highly suggest you make sure your Web app compiles to 32 bit if you're using COM objects, since they are almost guaranteed to be 32 bit and will crash in 64 bit if they are.
>>
>>To check what's really installed look in these folders:
>>
>>C:\Windows\Microsoft.NET\Framework
>>C:\Windows\Microsoft.NET\Framework64
>>
>>.NET 4.5 shows as .NET 4.0 but the build number will be v4.0.30319...
>>
>>If any project in your app uses .NET 4.5 your will have to run in .NET 4.5, so make sure you don't have one project set to 4.5 on your dev setup.
>
>Thanks, my project are set to 4.0. When I will switch to 4.5, I will make sure all the installation sites have .NET Framework 4.5.
>
>When I'll have time, I will get rid of the two Interop files I have. Both are not easy to replace as they do not offer support as is in the .NET Framework.
>
>For now, all my projects are Any CPU. And, those two interop files works well. The only thing is that I have a warning in the framework but that doesn't cause anything.
>
>Thanks for the input, that was very valuable.