After posting the initial issue, I did some further research. Although Microsoft has subtly encouraged not writing into the "Program Files" directory for years, Vista and Windows 7 take it a few steps further. Unless you really work at it, you can't write to the directory or sub-directories at all (I am referring to configuration files not the initial install)). The MasterDATA Plug-in (which allows reading .csv files directly by MetaStock) violated this rule, trying to write a configuration file to the "MetaStock\Equis" directory (which is within "Program Files" directory). Prior to Vista, this created no problems. It does now. Instead, from Vista on forward there is a new directory, "ProgramData", which is a central repository for programs to write their configuration files (etc) to. It is actually very efficient in that it is always in the same place and helps a program stay out of the registry (which is now the preferred practice). The bottom line is that the Plug-in is now a very well behaved program, installing and working very, very smoothly. Needless to say, this solved the problems I was having with the MDK also. Thanks for listening. I hope my experience will be helpful to some of you other coders out there. Best of luck. LPC http://masterdata.com