Make sure that in your IIS you have allowed for ASP debugging. Then, in InterDev, change to local mode (Project, Web Project, Working Mode, Local), and then you should be able to start the application. Be sure to have set a start page and when it prompts that first error message, just click on OK to get past it and you should be good to go.
All this is from memory, so if you have any other problems, just post again. Hope this helps.
Everything is absolute. Everything else is relative.