I recently ran into this problem when I accidentally started an ASP.NET
2.0 Web Services project in the wrong directory on my development
workstation. Thinking in the old VSNET 2003 mindset, I just moved the
project folder using Windows Explorer.
Realizing that the reference from the VSNET 2005 IDE Startup page would
be wrong, I drilled into the project directory via Windows Explorer
looking for the .SLN solution file. No file. Hmmm.
A few minutes of searching and I found the .SLN file in "My
Documents\Visual Studio 2005\Projects" folder. I don't know about
anyone else, but I absolutely dislike software putting files into the
"My Documents" directory, but I digress.
To fix the problem, I simply started Visual Studio 2005 and clicked my
project under "Recent Projects" on the Start Up Page. I got the
standard error about it not being able to find the project because it
had been moved. Right click on the Solution in the Solution Explorer
window of the IDE and choose ADD...Existing Web Site. Browse to the
new location of your ASP.NET project and click OPEN. VS2005 will pull
the project in and add it to your .SLN file.
It will now look like you have two projects in your solution -- the one
you just added, and the broken one where it couldn't find the project
that was moved. Simply right click on the broken project and remove
it.