in vs.net,there is a word (unavailable) beside the project item.
To correct the problem,use the same name in IIS as descriped in solution
file. For example,the virtual directory name should be CSharpBook
"http://localhost/CSharpBook/MyWebForm/MyWebForm.csproj",but i
used CSharpFaison in IIS,so when i took vs.net to open MyWebForm.sln in
CSharpFaison,vs.net prompted the above picture message and vs.net can't
open the project.
After change CSharpFaison to CSharpBook in IIS,the problem goes.