Is not a valid Win32 application. (exception from hresult: 0x800700c1)

Came authentication SS this nasty error the other day whilst trying to get an IIS app running on my visat 64bit PC:

Error: is not a valid Win32 application. (exception from hresult: 0x800700c1)

Solution:

1. Inside IIS (7) Click on application pools (left hand side under {machine_name }).
2. Find the application pool that is configured for your web application in the list.
3. Select it, then click Advanced Settings on the right.

4. Second setting in the list: Enable 32-bit applications-must be set to true.

But some time, not the case, Windows XP, iis5.1, thorw it.

I think something wrong with the IIS may be crashed.

Something may be like this.

Aspnet_regiis-I and restart.