I had to uninstalled FSX before due to some error in the system, but never had any problem with the PMDG installing untill now, I did installed Steam before , it was purchased a few years ago , but when i had to reinstalled FSX, i never reinstalled the Steam, at the same time never had no trouble installing the PMDG 737, its just recently that came up with me .
I always like to do a clean installed too when i do this , its crazy why this is doing that. I also have the PD3 V 4 install too no problem there so far.
I have both the FSX and the PD3v4 installed on the C drive. do not reckon they are interfering with the other would you?
Thanks