Got the following error, when I used the SharePoint dll in an ASP.NET project. VS2010 puts the sandbox assembly into the bin folder automatically.
Could not load file or assembly ‘Microsoft.Sharepoint.Sandbox, Version=126.96.36.199, Culture=neutral, PublicKeyToken=71e9bce111e9429c’ or one of its dependencies. An attempt was made to load a program with an incorrect format.
To fix the error, just delete the sandbox dll from the bin folder directly, but it is just temporary solution, VS2010 will create the dll again each time you do a build.
The final solution for me is to add the following commands to the Post – build event command line of the Build Events for this project.