I have a Windows 7 Ultimate SP1 x64 system with 8GB RAM, FSX with SP2 and PMDG's 747-X. All working perfectly. Today (Sept. 5, 2011) I purchased the 737NGX. When I run the installer, I receive an error dialog box that I have an "outdated version of FSX" and need to install SP2. However, SP2 is already installed on my FSX system. When I load an aircraft (747-X) and bring up the help/about menu, it shows that SP2 is installed. If I run the SP2 installer, it tells me that SP2 is already installed. My computer is equipped with removable drives. I removed my Windows 7 ultimate drive and replaced it with my Windows XP SP3 system with FSX. I ran the PMDG 737NGX installer and the same error message appeared--out of date FSX system that needs SP2, but SP2 is already installed. Does anyone have a clue why this is happening? Both operating systems are fully up-to-date with service packs and subsequent patches. Thanks in advance! Robert