I’ve got a very simple Solution with a single Project in it.
The project is just a simple WinForms, a config file to connect to sql-server, and 2 class files.
I’ve published the WinForms into production and it is working ok.
If I now open the Solution in VS and select the WinForms and press F5 I get an message “The Operation Can Not Be Completed” and the Winforms does not appear.
If, instead of F5 I use “Start Without Debugging” then it appears ok.
Should I be concerned about this message? If I should then how do I track down the reason behind it?
EDIT
Here are the debug options I have available:

YES! That is an Error Message!
In the Debug tab of YourProject there is a debugger option for “Enable the Visual Studio hosting process”.
for more info check
http://social.msdn.microsoft.com/Forums/en-US/vbide/thread/40d2d241-a0c0-4137-9da9-e40611972c0e/