There needs to be an "In Your Face" dialog that says you are about to checkout the Project file (AIIS) and, as such, you may be affecting other users with their work.  I often notice that I've got this file checked out but don't know what caused it or how long I've had the file checked out.  A modal dialog box that is presented when it happens would help me to understand what other action I've taken that caused the file to be checked out.  Furthermore, it would let me know to make such changes quickly so that the file can be checked back in as soon as possible.