I set OPTION STRICT ON as a default in VS2005 and also added it to the WEB.config file.

I noticed today in an ASP.net app I'm working on that the code wasn't throwing an error during implicit type conversions. Hmmm, that's strange...so after investigating every possiblility and multiple testing, I discovered that there's a bug in Visual Studio 2005.

This is the answer I got from Microsoft...

Sorry about the inconvenience.  There unfortunately isn’t a GUI way to enable option strict, but you can enable it by copying and pasting this statement into your application’s web.config file (it should go immediately underneath the root <configuration> element: 

  <system.codedom>
    <compilers>
      <compiler compilerOptions ="/optionexplicit+ /optionstrict+" language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.VisualBasic.VBCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    </compilers>
  </system.codedom> 

This will then enable option strict for both code-behind and your app_code directory. 

Hope this helps,

 

Scott