Will FMv9 work after installing FMv12?

Running Win7/64-bit. Have been running FMv7 and FMv9 for some time now.

Recently, I installed v12 and had tinkered with it for a few days before getting around to opening v9 - at which time I've discovered v9 will not start. With splash screen up, only Localization starts, and then "Internal Error 9004, 6921628, 9677518, 0. FrameMaker detected a serious problem and must quit."

I cannot know if v12 installation affected v9, since I had used my pc, worked business as usual, etc. for days before getting around to going into v9.

I am also tinkering with third part add-ons, so I might back track and find this myself. All I am really asking for at this point is for confirmation that v9 and v12 will can be expected to play nice together?

Thanks,

Dave