Greetings, all, I too sadly have the freezies at altitude. MB: ASUS M4N98TD EVOCPU: AMD Phenom II X6 1100T Black Edition 3.3 GHzRAM: 16GB Corsair Vengeance 4 x 4 GBSound card: Creative X-Fi Titanium HDVideo: ASUS GeForce 560 Ti (Fermi) OC 900 MHz DirectCU IIHD: System on 250 GB, FSX on 3 TB, archive 1 TB diskOS: Win 7 64-lousy-bit-edition So I built this computer specifically to run FSX like gangbusters. And it flies pretty nicely - until I get her up to altitude. Then, BOOM - instruments and all graphics freeze, no response. Sound continues as normal (as in a loop - tried pressing buttons that had sounds attached, but she wasn't responding.) Seems always to happen at high altitudes. I have to Task Manager it, and it of course unhelpfully says that FSX is "Not Responding". Event Viewer gives the classic "Event ID 101, 1002" error, and I go down and read the log and it says "Unknown..." in the hex to text entry. I had freezing before, but then I found my CPU cooler was loose and had an air gap in there... now it merely takes longer to freeze. Max temp before was a frightening 72 C, but now the highest it ever gets is 52 C using ASUS PC Probe II. So I thought I had ruled thermal issues out. GPU temp never gets over 45 or 46 C, monitored with their SmartDoctor technology and by ramping up the card's fans' speed. I've tried the UIAutomationCore.dll (Vista 32-bit) fix and every affinity mask setting you can think of. nVidia drivers installed 280.26, I think, newest available on their site. Newest sound card driver for the X-Fi Titanium, too (albeit in 2010, sheesh, old driver) Have not updated BIOS, however. That might be next on my list to try. I have FSX + SP1 + Acceleration installed, and also REX Overdrive (but it doesn't matter if I have REX running or not). Any opinions? I've ran stress tests on the CPU and RAM, specifically Prime95 and 3dMark11.