Questions on External Debugging in VS2010

Hi,

I am creating a grasshopper component these days in VS2010 with c#.  If I build a gha and make it run under grasshopper, everything is fine. I enjoyed this workflow, but found sometimes my component tuned red when running in grasshopper with an error message(img attached below). The error message does not indicate line numbers and I thought it was time for me to find a way of externally debugging my codes in VS2010(I don't know if this is a correct idea). I looked through all the posts in the forum and I set my "project properties" to externally open Rhino4.exe and changed my grasshopperDeveloperSettings. Rhino will successfully open when I hit debug but nothing happened afterwards. If I hit the pause button in VS, a tab appeared with a message "No Source Available"(img attached below). Do I miss something?

I do not have any experience in external debugging in VS but I think I have to find a way out.  Would it be possible for me to add to my component with an output parameter "out" and functions like "print" just like inside c# component in grasshopper? If this could, I would be able to print some messages out inside grasshopper and help myself to debug, otherwise, I may have to rely on the external debugging in VS.

I know it's possible to trace all the errors if I code inside a c# component in grasshopper but my code involves many classes. If I transfer my codes into the c# component, I have to deal with nested classes because only one class is allowed in one c# component. I found nested class quite complex to handle so I have to keep myself stick to VS.

Thanks,

-Jerome