I am currently using Visual C++ 4.1 under NT 3.51. I am also using a configuration management package called MKS Source Integrity which utilises file manager's associations to view files, i.e. if I associate .c, .cpp, .h, .rc etc files with VC++ under file manager then all these types of files will be viewed from within VC++. This is all pretty straightforward, however when I try to open a file from MKS or file manager when VC++ is already open, i.e. there ia already an instance of the application running, then another instance of VC++ is created. How can I setup VC++ to limit itself to only one application?