Check these two locations:
Tools | Options, Design Tab, check the "Project location for Visual Basic and C# code"
Tools | Form Options, Programming category, check the "Project location for Visual Basic and C# code"
If these paths do not exist or are inaccessible (such as permissions issues) you will not be able to add code to your solution. In that case, make sure to change these paths to existing locations of your choice.
David Airapetyan / Software Services ArchitectQdabra® Software / Streamline data gathering to turn process into knowledge