On one computer I'm using right now while away from home, W7home premium 64 bit. 
I just installed x3 studio and a couple of 3rd party 32 bit old standby plug I use. 
I have been working all week and have opened 24 or more projects. They're all from different years and set ups too. They all run fine. Only message I get is my DTX drums are not plugged in and one 3rd party reverb I forgot I'd used.  
SO I would start from the top and if you run into a problem work your way backwards. You may find there's no need for the older (buggy) versions at all.