I have an ATL COM component which wrapps the wincrypt api. In the post build I am calling tlbimp which generates an interop which is referenced in a C# CLR which is imported into SQL Server. This has all been working fine until a client made some changes (believe it to be permissions but the person who made the changes is no longer with the company so nobody really knows). Now when I try and call a sproc in the CLR I'm getting 'Object reference not set to an instance of an object'. Long shot I know but would anyone have any idea's?